HETEROCYCLES

Paper | Regular issue | Vol. 87, No. 1, 2013, pp. 91-113
Received, 28th October, 2012, Accepted, 16th November, 2012, Published online, 27th November, 2012.
DOI: 10.3987/COM-12-12613

■ Preparation of a Diverse Purine-Scaffold Library via One-Step Palladium Catalyzed Cross-Coupling

Tony Taldone,* Danuta Zatorska, Hardik J. Patel, Weilin Sun, Maulik R. Patel, and Gabriela Chiosis

Sloan-Kettering Institute, Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York 10065, U.S.A.

Abstract

In our ongoing efforts to prepare Hsp90 inhibitors, various cross-coupling reactions (Suzuki, Stille, Heck, and Sonogashira) were used to construct a diverse library of substituted purines in a single step from PU-H71 (1). We show that these reactions, particularly Suzuki coupling, are highly efficient, do not require protection of the pendant amine, and due to the wide variety of commercially available substrates, allow for the rapid development of a diverse purine library. The products derived from these reactions will enable us to explore the chemical space occupied by the key 6’-iodine of PU-H71 through molecules with diverse physical and chemical properties with the potential to be useful for diseases in which Hsp90 is implicated.

INTRODUCTION
The biological significance of purines and their derivatives as the endogenous ligand to a multitude of receptors, kinases, and ATPases implicated in disease has made it an attractive scaffold for chemical modification.1 As a result of this, as well as its ease of access to structural diversity, the purine ring has become a privileged structure in medicinal chemistry. Towards this goal, cross-coupling reactions have been used extensively to directly attach C-substituents (i.e. aryl, heteroaryl, alkenyl, alkyl) at positions 2, 6, or 8 of the purine-scaffold starting from the corresponding halopurine.2-4 In addition, these reactions may also be used to introduce diversity to purine-scaffolds whereby the purine ring remains unmodified.
A protein of significant interest to us that requires ATP for its function is heat shock protein 90 (Hsp90). Hsp90 is a molecular chaperone which assists in the conformational activation of its client proteins. Many of its clients (i.e. HER2, EGFR, mutant ER, HIF1α, Raf-1, AKT and mutant p53) function in the development and progression of cancer. As a result of this, as well as the ability to simultaneously inhibit multiple oncogenic signals, Hsp90 has emerged as an intriguing target in cancer and potentially in neurodegenerative diseases.5,6 One class of Hsp90 inhibitor discovered through rational design is based on the purine-scaffold, and in particular on 8-substituted adenines, as exemplified by the prototype PU3 (Scheme 1).7 Extensive medicinal chemistry efforts aimed at optimizing the potency and pharmacokinetic properties of PU3 have resulted in a number of agents currently in clinical trials for cancer including PU-H71 (1), MPC-3100 and CUDC-305 (Scheme 1).8 Each of these molecules have in common a purine or

purine-like core attached to a benzo[d][1,3]dioxolyl moiety at the 8-position through a sulfur linker. The benzo[d][1,3]dioxolyl moiety is substituted with a relatively small hydrophobic group in the 6'-position such as iodine, bromine or dimethylamine, which combined occupies a hydrophobic pocket of Hsp90 where it makes many critical interactions.9 The 6'-position, key for high-affinity binding to Hsp90 for this scaffold, has largely been unexplored because chemistry has not yet been developed. The presence of iodine in the 8-thioaryl substituent of 1 offered to us the intriguing possibility of performing single-step metal catalyzed cross-coupling reactions in an attempt to create a targeted and diverse library exploring the chemical space around the 6’-position (2; Scheme 1). In this paper we show that the Suzuki, Stille, Heck and Sonogashira coupling reactions can be used with great effect to generate a focused library of 6’-substituted 8-(benzo[d][1,3]dioxol-5-yl)thio purine analogs of the potent Hsp90 inhibitor PU-H71 (1) in a single step without the need for wasteful protection-deprotection steps (Scheme 1).

RESULTS AND DISCUSSION
Palladium catalyzed cross-coupling reactions have revolutionized the field of organic synthesis by enabling for the efficient construction of carbon-carbon bonds under mild conditions and with high functional group tolerance.10 Suzuki, Stille, Heck and Sonogashira coupling are some of the most commonly applied palladium-catalyzed cross-coupling reactions and their usefulness extends to the synthesis of complex natural products and of biologically active molecules. In this regard, these reactions have been used to construct novel scaffolds and to investigate structure activity relationships (SARs) through the rapid development of diverse molecular libraries. While there are numerous palladium catalyzed cross-coupling reactions available, we have chosen to focus on the Suzuki, Stille, Heck and Sonogashira reactions. Combined, these reactions complement one another and have enabled us access to a wide variety of derivatives of PU-H71 (1) through the direct substitution of the 6’-iodine on the 8-aryl ring (Tables 1-4). We show that these reactions are applicable to a complex heterocycle such as 1 and that they are tolerant of the secondary amine, thereby avoiding the necessity of tedious protection-deprotection steps.
Our general conditions for Suzuki coupling were heating a mixture of 1 with boronic acid (1.5-3 eq.), PdCl2(PPh3)2 (10-20 mol%) and NaHCO3 (3 eq.) in DMF/H2O at 90 °C for 2-24 h (Table 1). For the most part, 1.5 eq. of boronic acid and 10 mol% of PdCl2(PPh3)2 were sufficient, however, in cases where the reaction was noticeably sluggish, additional catalyst and/or boronic acid was added to ensure complete consumption of 1. Progress of the reaction was monitored by LC-MS as TLC proved inadequate for many of the reactions. Accordingly, it was essential to ensure complete reaction in order to efficiently isolate pure product. Therefore, the conditions reported including reaction time have not been optimized for yield, but rather reflect our requirement for complete consumption of starting material. As can be seen in Table 1, a

large number of products were obtained from the reaction of 1 with 5- and 6-membered aromatic and heteroaromatic boronic acids as well as with an alkenyl boronic acid.
Reaction of 1 with phenylboronic acid and 4-tert-butylphenylboronic acid yielded 3 and 4, respectively, in good yields. The reaction was tolerant to a wide variety of functional groups and was unaffected by the presence of electron donating or withdrawing groups on the phenyl ring. The 4-methoxy, 3-methoxy, 2,3-dimethoxy and 4-dimethylamino derivatives 5-8 were each prepared in good yield. The 4-formyl and 4-bromo derivatives 9-10, as well as the strongly electron withdrawing 3-cyano, 3-nitro, 3-trifluoromethyl and 3,5-di-trifluoromethyl derivatives 11-14 were formed in moderate to good yields. The reaction of 1 with 4-aminomethylphenylboronic acid yielded 15 in 30% and its N-formyl derivative in 17% as a by-product from the further reaction of the primary amine with the DMF solvent. Heterocyclic boronic acids also reacted with 1 to give pyridine 16, thiophene 17, furans 18-21, pyrroles 22-23, and pyrazoles 24-26. Under the general conditions employed, the product 27 desired in the reaction with 4-isoxazoleboronic acid pinacol ester was not obtained. Instead, nitrile 28 was isolated, presumably as a result of CO elimination from isoxazole 27, in 49% yield. A similar occurrence has been mentioned previously in the coupling of 4-isoxazoleboronic acid pinacol ester with a fused 2-bromoimidazole.11 Furthermore, acetonitrile and CO were identified as the major products from the thermal decomposition of isoxazole.12 In an attempt to isolate isoxazole 27, the reaction temperature was lowered to 60 °C, however, an inseperable mixture of isoxazole 27 and nitrile 28 was obtained in a ratio of 71:29, respectively, as determined by LC-MS. However, conducting the reaction at rt for 24 h yielded 27 in 43% yield with no formation of nitrile 28.
While reaction of 1 with a substituted alkenyl boronic acid yielded vinylic compound 29 in 66% yield, alkyl boronic acids failed to react under our general conditions. Reactions with methylboronic acid, 2-methylpropylboronic acid, phenethylboronic acid and cyclopropylboronic acid resulted in no product as determined by LC-MS. Using conditions previously described as optimal for the coupling of cyclopropylboronic acid with aryl bromides ((Pd(OAc)2, tricyclohexylphosphine, toluene, H2O, K3PO4, 100 °C)13 resulted in no reaction after 3 h. Prolonged heating for 24-48 h with excess cyclopropylboronic acid (3 eq.), Pd(OAc)2, (20 mol%) and tricyclohexylphosphine (0.2 eq.) resulted in an inseparable mixture of unreacted starting material 1, product and deiodinated reduced material.
Although Stille coupling accomplishes similar transformations to Suzuki coupling, they complement each other through the availability of respective starting materials and hence expand the scope of products that may be obtained in one-step reactions. Our initial attempts of Stille coupling aryl tin compounds with 1 or even Boc-protected 1 were unsuccessful and resulted in significant protodestannylation as well as

unreacted starting material, with only very minor amount of product detectable. However, the addition of LiCl to the reaction resulted in smooth conversion to product with no detectable protodestannylation and was the key to the success of this reaction. LiCl is commonly used to promote Stille couplings14,15 and is believed to function through the exchange of chloride ion with the coordinated iodide ion in the oxidative addition product. The resulting chloro complex facilitates transmetalation with arylstannane through the formation of stable Bu3SnCl. The general conditions we adopted ((n-Bu)3SnR (4 eq.), LiCl (2 eq.), Pd(PPh3)4 (10-20 mol%), DMF, 90-100 °C, 18 h) were used to prepare a number of 5- and 6-membered aromatics as well as the vinyl and allyl derivatives (Table 2). In order to demonstrate the usefulness of Stille coupling and to expand the diversity of our library, the compounds formed (Table 2) were chosen to be distinct from those produced by Suzuki coupling (Table 1).
The 4-benzyloxy and 4-morpholine substituted phenyl derivatives 30 and 31, respectively, as well as pyrimidine 32 and pyrazine 33 were obtained by reaction with respective tri-n-butyltin compounds in moderate yields. Other heterocycles including oxazole 34, thiazole 35, and imidazole 36 were similarly prepared. The vinyl and allyl groups can also be added through Stille coupling by reaction with tri-n-butylvinyltin or tri-n-butylallyltin to give 37 or 38, respectively. Although Stille and Suzuki reactions complement each other well, a major disadvantage of the Stille reaction is the use of toxic organotin compounds. In comparison to the boronic acids used in Suzuki coupling, organotin compounds are much more toxic and must be handled with great care.
Our general conditions for Heck coupling consisted of heating a mixture of purine 1 with alkene (1.1-20 eq.), Pd(PPh3)4 (10-20 mol%) and N,N-diisopropylethylamine (1.2-2 eq.) in NMP at 55-100 °C for 20-24 h (Table 3). Reaction with methyl acrylate and acrylonitrile yielded the trans-substituted products 39 and 40, respectively. As expected, reaction with each of the cyclic alkenes occurred with migration of the double bond.16,17 The major isolatable product obtained from the reaction with cyclopentene is the 2,3-alkene 41, whereas in the reaction with 2,5-dihydrofuran, the double bond flips to the 2,3-position to give 42. In the case of the unsymmetrical alkenes, enol ether 2,3-dihydrofuran and N-protected enamine 2,3-dihydropyrrole, reaction occurs at the carbon adjacent to the heteroatom. 43 was obtained as the major product from reaction with 2,3-dihydrofuran, while reaction with N-Boc-2,3-dihydropyrrole results in the double bond flipping to the 3,4-position of the pyrrolidine ring, yielding 44 as the major product following deprotection.
1 can also undergo the Sonogashira reaction with a variety of alkynes without protection of the amine in moderate to good yields (Table 4). Our general conditions consisted of heating a mixture of purine 1 with alkyne (2-2.5 eq.), PdCl2(PPh3)2 (15 mol%), CuI (0.5 eq.) and triethylamine (5 eq.) in DMF at 90-100 °C for 24 h (Table 4). The unsubstituted alkyne derivative 45 was prepared from trimethylsilanylacetylene

following removal of the trimethylsilyl group. Other acetylene derivatives of 1 obtained in moderate to good yields using our general conditions include n-butyl 46, t-butyl 47, cyclopentyl 48, cyclohexyl 49 and phenyl 50.

CONCLUSION
We have shown that Pd-catalyzed cross-coupling reactions can be used to prepare a library of derivatives of PU-H71 (1) in a single step with commercially available reagents. These reactions occur on an “advanced intermediate” without the need of protecting groups and enable for late stage introduction of chemical diversity to generate a focused library of 6’-substituted 8-(benzo[d][1,3]dioxol-5-yl)thio purines. Suzuki

and Stille coupling were used to introduce a variety of aryl or alkenyl groups to 1. Heck coupling enabled for the reaction with a variety of olefins, while Sonogashira coupling was used to introduce a variety of alkynes. In general, Suzuki coupling occurred with smooth conversion to the desired product and only in the case of 4-isoxazoleboronic acid pinacol ester was the expected product 27 not isolated using the general conditions. However, performing the reaction at rt allowed for the isolation of 27 and prevented its decomposition to nitrile 28. In the case of Stille coupling, the addition of LiCl was found to be essential for the success of the reaction by enabling efficient transmetalation. The wide variety and ready availability of boronic acids, as well as their non-toxic nature, has made Suzuki coupling the most useful reaction of those reported here to construct the library of substituted purines in a single step from PU-H71 (1). Because of the significance of 1 as a potent Hsp90 inhibitor which has entered clinical trials as an anticancer agent,8 we believe that this library has significant value for biological investigations which Hsp90 has been associated with.

EXPERIMENTAL
GENERAL METHODS
1H and 13C NMR spectra were recorded on a Bruker 500 or 600 MHz instrument. Chemical shifts are reported in δ values in ppm downfield from TMS as the internal standard. 1H data are reported as follows: chemical shift, multiplicity (s = singlet, d = doublet, t = triplet, q = quartet, br = broad, m = multiplet), coupling constant (Hz), integration. 13C chemical shifts are reported in δ values in ppm downfield from TMS as the internal standard. High resolution mass spectra (HRMS) were recorded on a Waters LCT Premier system. Low resolution mass spectra were obtained on a Waters Acquity Ultra Performance LC with electrospray ionization and SQ detector. High-performance liquid chromatography analyses were performed on a Waters Autopurification system with PDA, MicroMass ZQ, and ELSD detector, and a reversed phase column (Waters X-Bridge C18, 4.6 x 150 mm, 5 µm) using a gradient of; method A (a) H2O + 0.1% TFA and (b) CH3CN + 0.1% TFA, 5 to 95% b over 10 min at 1.2 mL/min; method B (a) H2O + 0.1% TFA and (b) CH3CN + 0.1% TFA, 20 to 90% b over 16 min at 1.0 mL/min. PU-H71 was prepared as previously reported.18 All reagents were purchased from Aldrich, Acros, Combi-blocks or Frontier Scientific.

SUZUKI-MIYAURA COUPLING
General conditions. Boronic acid or pinacol ester (1.5-3 eq.) was added to 1 (30 mg, 0.0585 mmol, 1 eq.) and NaHCO3 (3 eq.) in a 10 mL RBF equipped with a magnetic stir bar and rubber septum. DMF (0.5 mL) was added and the reaction mixture was evacuated and back filled with nitrogen. This was repeated four times then nitrogen was bubbled through the reaction mixture for 10 min. Then H2O (0.1 mL) and PdCl2(PPh3)2 (10-20 mol%) were added and the reaction mixture was heated under nitrogen at 90 °C for 2-24 h. Solvent was removed under reduced pressure and the resulting residue was purified by preparatory TLC to yield compounds 3-26, 28 and 29. 27 was obtained by performing the reaction at rt as is described below.
9-(3-(Isopropylamino)propyl)-8-(6-phenylbenzo[d][1,3]dioxol-5-ylthio)-9H-purin-6-amine (3). 1H NMR (500 MHz, MeOH-d4) δ 8.14 (s, 1H), 7.28-7.34 (m, 3H), 7.17-7.21 (m, 2H), 7.12 (s, 1H), 6.90 (s, 1H), 6.09 (s, 2H), 4.03 (t, J = 6.4 Hz, 2H), 3.27 (septet, J = 6.6 Hz, 1H), 2.72 (t, J = 6.6 Hz, 2H), 2.13 (m, 2H), 1.40 (d, J = 6.5 Hz, 6H); 13C NMR (125 MHz, MeOH-d4) δ 156.0, 153.4, 152.1, 151.1, 150.3, 149.4, 142.3, 141.8, 130.4, 129.1, 128.7, 120.3, 119.8, 115.7, 112.2, 103.8, 52.2, 43.2, 41.1, 27.6, 19.3; HRMS (ESI) m/z [M+H]+ calcd. for C24H27N6O2S, 463.1916; found 463.1905; HPLC: method A Rt = 6.50,
method B Rt = 7.40. 8-(6-(4-tert-Butylphenyl)benzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (4). 1H NMR (500 MHz, MeOH-d4) δ 8.11 (s, 1H), 7.27 (d, J = 8.4 Hz, 2H), 7.14 (s, 1H), 7.12 (d, J = 8.4 Hz, 2H), 6.86 (s, 1H), 6.06 (s, 2H), 3.93 (t, J = 6.9 Hz, 2H), 2.92 (septet, J = 6.5 Hz, 1H), 2.61 (t, J = 7.3 Hz, 2H), 1.86 (m, 2H), 1.28 (s, 9H), 1.12 (d, J = 6.5 Hz, 6H); 13C NMR (125 MHz, MeOH-d4) δ 155.9, 153.3, 151.9, 151.8, 150.9, 150.2, 149.2, 141.9, 138.8, 130.0, 125.9, 120.4, 120.3, 115.4, 112.3,103.6, 50.6, 44.0, 41.8, 35.4, 31.8, 29.3, 21.1; HRMS (ESI) m/z [M+H]+ calcd. for C28H35N6O2S,519.2542; found 519.2545; HPLC: method A Rt = 7.43, method B Rt = 9.45.
9-(3-(Isopropylamino)propyl)-8-(6-(4-methoxyphenyl)benzo[d][1,3]dioxol-5-ylthio)-9H-purin-6-amine (5). 1H NMR (500 MHz, CDCl3) δ 8.25 (s, 1H), 7.19 (d, J = 8.7 Hz, 2H), 6.95 (s, 1H), 6.86 (d, J = 8.7 Hz, 2H), 6.82 (s, 1H), 6.00 (s, 2H), 5.92 (br s, 2H), 4.01 (t, J = 6.7 Hz, 2H), 3.82 (s, 3H), 2.75 (septet, J = 6.3 Hz, 1H), 2.43 (t, J = 6.7 Hz, 2H), 1.85 (m, 2H), 1.07 (d, J = 6.3 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 159.2, 154.3, 152.5, 151.5, 148.6, 147.8, 147.5, 139.0, 132.5, 130.4, 120.6, 119.8, 113.5, 113.0, 111.0, 101.8, 55.3, 49.1, 43.2, 40.9, 29.2, 22.2; HRMS (ESI) m/z [M+H]+ calcd. for C25H29N6O3S, 493.2022; found 493.2010; HPLC: method A Rt = 6.57, method B Rt = 7.55.
9-(3-(Isopropylamino)propyl)-8-(6-(3-methoxyphenyl)benzo[d][1,3]dioxol-5-ylthio)-9H-purin-6-amine (6). 1H NMR (500 MHz, CDCl3) δ 8.19 (s, 1H), 7.16 (t, J = 8.0 Hz, 1H), 6.91 (s, 1H), 6.73-6.81 (m, 3H), 6.70 (s, 1H), 5.93 (s, 2H), 5.82 (br s, 2H), 3.91 (t, J = 6.9 Hz, 2H), 3.63 (s, 3H), 2.59 (septet, J = 6.2 Hz, 1H), 2.32 (t, J = 6.8 Hz, 2H), 1.66-1.75 (m, 2H), 0.93 (d, J = 6.3 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 159.9, 154.9, 153.2, 152.1, 149.2, 148.3, 142.1, 139.8, 129.7, 122.3, 121.4, 120.5, 115.5, 113.9, 111.5, 102.6, 55.8, 49.4, 44.2, 41.8, 30.5, 23.4; HRMS (ESI) m/z [M+H]+ calcd. for C25H29N6O3S, 493.2022; found 493.2036.
8-(6-(2,3-Dimethoxyphenyl)benzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (7). 1H NMR (500 MHz, CDCl3) δ 8.18 (s, 1H), 6.88-6.94 (m, 2H), 6.86 (d, J = 8.0 Hz, 1H), 6.74 (s, 1H), 6.62 (d, J = 7.5 Hz, 1H), 5.92 (s, 2H), 5.88 (br s, 2H), 3.75-4.05 (m, 2H), 3.82 (s, 3H), 3.54 (s, 3H), 2.59 (septet, J = 6.2 Hz, 1H), 2.30 (t, J = 6.6 Hz, 2H), 1.64-1.74 (m, 2H), 0.93 (d, J = 6.1 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 155.0, 153.4, 153.2, 152.2, 148.8, 148.4, 148.3, 147.3, 135.5, 134.9, 124.3, 123.3, 122.9, 120.5, 113.5, 112.9, 111.6, 102.5, 61.4, 56.5, 49.4, 44.2, 41.7, 30.4, 23.3; HRMS (ESI) m/z [M+H]+ calcd. for C26H31N6O4S, 523.2128; found 523.2107.
8-(6-(4-(Dimethylamino)phenyl)benzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (8). 1H NMR (500 MHz, CDCl3) δ 8.24 (s, 1H), 7.13 (d, J = 8.7 Hz, 2H), 6.93 (s, 1H), 6.83 (s, 1H), 6.67 (d, J = 8.7 Hz, 2H), 6.01 (br s, 2H), 5.98 (s, 2H), 4.02 (t, J = 6.7 Hz, 2H), 2.97 (s, 6H), 2.78 (septet, J = 6.3 Hz, 1H), 2.44 (t, J = 6.7 Hz, 2H), 1.87 (m, 2H), 1.10 (d, J = 6.3 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 154.4, 152.4, 151.5, 149.9, 148.5, 148.0, 147.1, 139.6, 130.0, 127.8, 120.5, 119.7, 112.8, 111.7, 111.0, 101.7, 49.3, 43.1, 40.9, 40.4, 28.9, 21.9; HRMS (ESI) m/z [M+H]+ calcd. for C26H32N7O2S, 506.2338; found 506.2330; HPLC: method A Rt = 5.72, method B Rt = 5.12.
4-(6-(6-Amino-9-(3-(isopropylamino)propyl)-9H-purin-8-ylthio)benzo[d][1,3]dioxol-5-yl)benzaldehyde (9). 1H NMR (500 MHz, MeOH-d4) δ 10.01 (s, 1H), 8.15 (s, 1H), 7.85 (d, J = 8.1 Hz, 2H), 7.47 (d, J = 8.1 Hz, 2H), 7.14 (s, 1H), 6.93 (s, 1H), 6.13 (s, 2H), 4.05 (t, J = 6.8 Hz, 2H), 2.99 (septet, J = 6.4 Hz, 1H), 2.62 (t, J = 6.9 Hz, 2H), 1.99 (m, 2H), 1.24 (d, J = 6.4 Hz, 6H); 13C NMR (125 MHz, MeOH-d4) δ 192.3, 154.1, 151.9, 151.0, 149.8, 148.8, 148.5, 146.4, 139.5, 135.3, 130.0, 129.4, 119.0, 117.7, 115.0, 110.8, 102.4, 49.9, 42.2, 40.3, 27.4, 20.2; HRMS (ESI) m/z [M+H]+ calcd. for C25H27N6O3S, 491.1865; found 491.1877; HPLC: method A Rt = 6.23, method B Rt = 6.83.
8-(6-(4-Bromophenyl)benzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (10). 1H NMR (500 MHz, CDCl3) δ 8.23 (s, 1H), 7.44 (d, J = 8.2 Hz, 2H), 7.13 (d, J = 8.2 Hz, 2H), 7.01 (s, 1H), 6.81 (s, 1H), 6.05 (s, 2H), 5.69 (br s, 2H), 4.08 (t, J = 6.0 Hz, 2H), 2.91 (m, 1H), 2.50 (t, J = 5.9 Hz, 2H), 1.98 (m, 2H), 1.20 (d, J = 6.4 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 154.2, 152.0, 151.2, 149.8, 149.1, 148.2, 139.8, 139.1, 131.2, 131.0, 122.0, 119.0, 117.9, 115.0, 111.1, 102.4, 50.1, 42.1, 40.2, 27.3, 20.2; HRMS (ESI) m/z [M+H]+ calcd. for C24H26BrN6O2S, 541.1021/543.1001; found 541.1016/543.1004; HPLC: method A Rt = 6.93, method B Rt = 8.30.
3-(6-(6-Amino-9-(3-(isopropylamino)propyl)-9H-purin-8-ylthio)benzo[d][1,3]dioxol-5-yl)benzonitrile (11). 1H NMR (500 MHz, CDCl3) δ 8.19 (s, 1H), 7.55 (s, 1H), 7.52 (d, J = 7.7 Hz, 1H), 7.45 (d, J = 7.9 Hz, 1H), 7.31-7.36 (m, 1H), 6.95 (s, 1H), 6.73 (s, 1H), 5.97 (s, 2H), 5.74 (br s, 2H), 3.97 (t, J = 6.9 Hz, 2H), 2.63 (septet, J = 6.2 Hz, 1H), 2.39 (t, J = 6.7 Hz, 2H), 1.72-1.81 (m, 2H), 0.96 (d, J = 6.3 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 154.8, 153.2, 152.2, 149.8, 149.0, 148.0, 142.0, 138.0, 134.4, 133.6, 131.8, 129.5, 120.8, 120.5, 119.1, 114.8, 112.9, 111.4, 102.9, 49.5, 44.1, 41.8, 30.4, 23.3; HRMS (ESI) m/z [M+H]+ calcd. for C25H26N7O2S, 488.1869; found 488.1878.
9-(3-(Isopropylamino)propyl)-8-(6-(3-nitrophenyl)benzo[d][1,3]dioxol-5-ylthio)-9H-purin-6-amine (12). 1H NMR (500 MHz, CDCl3) δ 8.17 (s, 1H), 8.16 (s, 1H), 8.09 (d, J = 8.1 Hz, 1H), 7.56 (d, J = 7.5 Hz, 1H), 7.37-7.43 (m, 1H), 6.99 (s, 1H), 6.78 (s, 1H), 5.99 (s, 2H), 5.77 (br s, 2H), 3.97 (t, J = 6.7 Hz, 2H), 2.60 (septet, J = 6.1 Hz, 1H), 2.37 (t, J = 6.6 Hz, 2H), 1.70-1.80 (m, 2H), 0.94 (d, J = 6.2 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 154.8, 153.2, 152.2, 149.9, 149.1, 148.5, 148.0, 142.3, 138.0, 136.1, 129.6, 125.1, 123.1, 120.7, 120.4, 115.0, 111.4, 102.9, 49.5, 44.1, 41.8, 30.5, 23.2; HRMS (ESI) m/z [M+H]+ calcd. for C24H26N7O4S, 508.1767; found 508.1772.
9-(3-(Isopropylamino)propyl)-8-(6-(3-(trifluoromethyl)phenyl)benzo[d][1,3]dioxol-5-ylthio)-9H-purin-6-amine (13). 1H NMR (500 MHz, CDCl3) δ 8.17 (s, 1H), 7.45-7.51 (m, 2H), 7.32-7.40 (m, 2H), 6.99 (s, 1H), 6.76 (s, 1H), 5.98 (s, 2H), 5.70 (br s, 2H), 3.91 (t, J = 6.9 Hz, 2H), 2.60 (septet, J = 6.3 Hz, 1H), 2.34 (t, J = 6.7 Hz, 2H), 1.68-1.76 (m, 2H), 0.94 (d, J = 6.3 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 154.8, 153.2, 152.2, 149.7, 148.8, 148.2, 141.5, 138.9, 133.3, 131.1 (q, J = 33 Hz), 129.1, 126.8 (q, J = 4 Hz), 125.0 (q, J = 4 Hz) 124.6 (q, J = 271 Hz), 120.9, 120.4, 114.8, 111.6, 102.8, 49.5, 44.1, 41.7, 30.4, 23.2; HRMS (ESI) m/z [M+H]+ calcd. for C25H26F3N6O2S, 531.1790; found 531.1780.
8-(6-(3,5-Bis(trifluoromethyl)phenyl)benzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (14). 1H NMR (500 MHz, CDCl3) δ 8.22 (s, 1H), 7.79 (s, 3H), 7.12 (s, 1H), 6.86 (s, 1H), 6.09 (s, 2H), 5.71 (br s, 2H), 4.07 (t, J = 6.6 Hz, 2H), 2.82 (septet, J = 6.2 Hz, 1H), 2.49 (t, J = 6.5 Hz, 2H), 1.95 (m, 2H), 1.12 (d, J = 6.3 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 154.1, 152.3, 151.5, 149.6, 148.6, 147.5, 142.1, 137.2, 131.2 (q, J = 33 Hz), 129.6, 123.1 (q, J = 270 Hz), 121.3, 119.6, 119.4, 114.9, 110.8, 102.4, 49.5, 42.8, 40.6, 28.8, 21.7; HRMS (ESI) m/z [M+H]+ calcd. for C26H25F6N6O2S, 599.1664; found 599.1653; HPLC: method A Rt = 7.45, method B Rt = 9.38.
8-(6-(4-(Aminomethyl)phenyl)benzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (15). 1H NMR (500 MHz, CDCl3) δ 8.19 (s, 1H), 7.22 (d, J = 8.0 Hz, 2H), 7.15 (d, J = 8.0 Hz, 2H), 6.91 (s, 1H), 6.75 (s, 1H), 5.95 (s, 2H), 5.59 (br s, 2H), 3.90 (t, J = 6.9 Hz, 2H), 3.81 (s, 2H), 2.60 (septet, J = 6.3 Hz, 1H), 2.33 (t, J = 6.8 Hz, 2H), 1.65-1.74 (m, 2H), 0.94 (d, J = 6.2 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 154.9, 153.3, 152.2, 149.2, 148.29, 148.26, 143.4, 139.7, 139.3, 130.1, 127.5, 121.4, 120.6, 113.8, 111.6, 102.6, 49.4, 46.8, 44.2, 41.9, 30.5, 23.3; HRMS (ESI) m/z [M+H]+ calcd. for C25H30N7O2S, 492.2182; found 492.2170.
From above reaction 4.8 mg (17%) of N-formyl derivative of 15 was also obtained.
N-(4-(6-(6-Amino-9-(3-(isopropylamino)propyl)-9H-purin-8-ylthio)benzo[d][1,3]dioxol-5-yl)benzyl) formamide. 1H NMR (500 MHz, CDCl3) δ 8.25 (s, 1H), 8.15 (s, 1H), 7.11 (d, J = 7.9 Hz, 2H), 7.08 (s, 1H), 7.02 (d, J = 7.9 Hz, 2H), 6.73 (s, 1H), 5.98 (s, 2H), 5.59 (br s, 2H), 4.40 (d, J = 6.0 Hz, 2H), 3.73 (t, J = 6.8 Hz, 2H), 2.75 (septet, J = 6.3 Hz, 1H), 2.37 (t, J = 6.8 Hz, 2H), 1.64-1.73 (m, 2H), 1.04 (d, J = 6.3 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 162.0, 154.9, 153.0, 151.8, 149.7, 148.9, 148.3, 140.4, 140.2, 138.3, 130.2, 128.2, 121.0, 120.5, 115.2, 111.7, 102.7, 50.0, 43.7, 42.3, 41.5, 29.7, 22.6; HRMS (ESI) m/z [M+H]+ calcd. for C26H30N7O3S, 520.2131; found 520.2145.
9-(3-(Isopropylamino)propyl)-8-(6-(pyridin-4-yl)benzo[d][1,3]dioxol-5-ylthio)-9H-purin-6-amine(16). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.53 (dd, J = 1.6, 4.8 Hz, 2H), 8.19 (s, 1H), 7.25 (dd, J = 1.6, 4.5 Hz, 2H), 7.11 (s, 1H), 6.89 (s, 1H), 6.11 (s, 2H), 4.07 (t, J = 6.8 Hz, 2H), 2.82 (m, 1H), 2.51 (t, J = 6.8 Hz, 2H), 1.91 (m, 2H), 1.13 (d, J = 6.3 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 154.1, 152.0, 151.2, 150.0, 148.90, 148.85, 148.69, 137.9, 124.5, 119.1, 117.7, 115.3, 110.6, 102.5, 49.2, 42.8, 40.7, 28.4, 21.2; HRMS (ESI) m/z [M+H]+ calcd. for C23H26N7O2S, 464.1869; found 464.1848; HPLC: method A Rt = 5.13, method B Rt = 2.57.
9-(3-(Isopropylamino)propyl)-8-(6-(thiophen-2-yl)benzo[d][1,3]dioxol-5-ylthio)-9H-purin-6-amine(17). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.17 (s, 1H), 7.33 (dd, J = 1.4, 4.9 Hz, 1H), 7.07 (s, 1H), 7.04 (s, 1H), 7.00-7.02 (m, 2H), 6.09 (s, 2H), 4.12 (t, J = 6.6 Hz, 2H), 2.95 (septet, J = 6.6 Hz, 1H), 2.62 (t, J = 6.8 Hz, 2H), 2.00 (m, 2H), 1.19 (d, J = 6.6 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 154.2, 152.0, 151.1, 149.4, 148.8, 148.4, 140.5, 132.9, 127.8, 126.9, 126.3, 119.2, 119.0, 114.6, 111.8, 102.3, 49.6, 42.5, 40.6, 27.8, 20.7; HRMS (ESI) m/z [M+H]+ calcd. for C22H25N6O2S2, 469.1480; found 469.1461; HPLC: method A Rt = 6.38, method B Rt = 7.18.
8-(6-(Furan-2-yl)benzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (18). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.18 (s, 1H), 7.49 (d, J = 1.8 Hz, 1H), 7.25 (s, 1H), 6.96 (s, 1H), 6.71 (d, J = 3.3 Hz, 1H), 6.47 (dd, J = 1.8, 3.2 Hz, 1H), 6.06 (s, 2H), 4.20 (t, J = 7.0 Hz, 2H), 2.87 (m, 1H), 2.61 (t, J = 6.9 Hz, 2H), 2.00 (m, 2H), 1.14 (d, J = 6.3 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 154.3, 152.2, 151.2, 150.9, 149.5, 148.14, 148.08, 142.4, 129.0, 119.2, 117.5, 114.5, 111.5, 110.0, 109.0, 102.3, 42.8, 41.0, 28.5, 21.2; HRMS (ESI) m/z [M+H]+ calcd. for C22H25N6O3S, 453.1709; found 453.1705; HPLC: method A Rt = 6.23, method B Rt = 6.82.
9-(3-(Isopropylamino)propyl)-8-(6-(5-methylfuran-2-yl)benzo[d][1,3]dioxol-5-ylthio)-9H-purin-6-amine (19). 1H NMR (500 MHz, CDCl3) δ 8.25 (s, 1H), 7.19 (s, 1H), 6.84 (s, 1H), 6.63 (d, J = 3.1 Hz, 1H), 6.07 (d, J = 2.5 Hz, 1H), 5.98 (s, 2H), 5.93 (br s, 2H), 4.22 (t, J = 6.6 Hz, 2H), 2.94 (m, 1H), 2.59 (t, J = 6.6 Hz, 2H), 2.34 (s, 3H), 2.05 (m, 2H), 1.20 (d, J = 6.3 Hz, 6H); HRMS (ESI) m/z [M+H]+ calcd. for C23H27N6O3S, 467.1865; found 467.1869; HPLC: method A Rt = 6.49, method B Rt = 7.53.
5-(6-(6-Amino-9-(3-(isopropylamino)propyl)-9H-purin-8-ylthio)benzo[d][1,3]dioxol-5-yl)furan-2-carbaldehyde (20). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 9.57 (s, 1H), 8.18 (s, 1H), 7.36 (d, J = 3.8 Hz, 1H), 7.32 (s, 1H), 7.07 (s, 1H), 6.98 (d, J = 3.8 Hz, 1H), 6.12 (s, 2H), 4.32 (t, J = 6.7 Hz, 2H), 3.31 (septet, J = 6.6 Hz, 1H), 2.93 (t, J = 6.8 Hz, 2H), 2.30 (m, 2H), 1.42 (d, J = 6.6 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 177.5, 156.8, 154.5, 152.2, 151.9, 151.4, 150.1, 149.7, 148.1, 127.5, 124.3, 119.2, 118.7, 115.7, 112.7, 109.9, 102.9, 51.3, 41.8, 40.4, 26.4, 19.2; HRMS (ESI) m/z [M+H]+ calcd. for C23H25N6O4S, 481.1658; found 481.1657; HPLC: method A Rt = 5.87, method B Rt = 5.93.
8-(6-(Furan-3-yl)benzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (21). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.17 (s, 1H), 7.51 (s, 1H), 7.44 (s, 1H), 7.07 (s, 1H), 6.97 (s, 1H), 6.49 (s, 1H), 6.08 (s, 2H), 4.17 (t, J = 6.9 Hz, 2H), 2.93 (septet, J = 6.4 Hz, 1H), 2.64 (t, J = 7.1 Hz, 2H), 2.02 (m, 2H), 1.17 (d, J = 6.4 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 154.1, 151.8, 151.0, 149.7, 149.0, 147.8, 142.6, 140.4, 131.7, 124.2, 118.9, 117.8, 114.8, 111.5, 110.7, 102.1, 49.2, 42.6, 40.6, 28.0, 20.7; HRMS (ESI) m/z [M+H]+ calcd. for C22H25N6O3S, 453.1709; found 453.1711; HPLC: method A Rt = 6.18, method B Rt = 6.67.
8-(6-(1H-Pyrrol-2-yl)benzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (22). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.17 (s, 1H), 7.04 (s, 1H), 7.01 (s, 1H), 6.88 (m, 1H), 6.27 (m, 1H), 6.21 (m, 1H), 6.03 (s, 2H), 4.17 (t, J = 6.8 Hz, 2H), 3.29 (septet, J = 6.6 Hz, 1H), 2.80 (t, J = 6.7 Hz, 2H), 2.15 (m, 2H), 1.41 (d, J = 6.6 Hz, 6H); HRMS (ESI) m/z [M+H]+ calcd. for C22H26N7O2S, 452.1869; found 452.1872; HPLC: method A Rt = 6.13, method B Rt = 6.43.
8-(6-(1H-Pyrrol-3-yl)benzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (23). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.16 (s, 1H), 7.02 (s, 1H), 6.99 (s, 1H), 6.86 (m, 1H), 6.76 (m, 1H), 6.21 (m, 1H), 6.02 (s, 2H), 4.07 (t, J = 6.9 Hz, 2H), 2.95 (septet, J = 6.4 Hz, 1H), 2.59 (t, J = 7.1 Hz, 2H), 1.96 (m, 2H), 1.19 (d, J = 6.4 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 154.4, 152.1, 152.0, 151.0, 149.4, 146.7, 135.9, 131.6, 122.1, 119.1, 117.8, 117.5, 114.6, 111.0, 109.2, 101.9, 53.6, 42.6, 40.6, 27.8, 20.6; HRMS (ESI) m/z [M+H]+ calcd. for C22H26N7O2S, 452.1869; found 452.1862; HPLC: method A Rt = 6.02, method B Rt = 6.27.
8-(6-(1H-Pyrazol-3-yl)benzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (24). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.17 (s, 1H), 7.59 (d, J = 2.0 Hz, 1H), 7.10 (s, 1H), 7.07 (s, 1H), 6.38 (d, J = 2.0 Hz, 1H), 6.08 (s, 2H), 4.19 (t, J = 6.8 Hz, 2H), 3.31 (septet, J = 6.6 Hz, 1H), 2.89 (t, J = 7.2 Hz, 2H), 2.10 (m, 2H), 1.39 (d, J = 6.6 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 154.5, 152.2, 152.1, 150.7, 149.5, 148.5, 148.3, 119.3, 119.1, 114.6, 114.5, 111.0, 110.9, 106.1, 102.3, 51.1, 41.7, 40.3, 26.0, 18.7; HRMS (ESI) m/z [M+H]+ calcd. for C21H25N8O2S, 453.1821; found 453.1826; HPLC: method A Rt = 5.65, method B Rt = 4.83.
8-(6-(1H-Pyrazol-4-yl)benzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (25). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.17 (s, 1H), 7.58 (s, 2H), 7.10 (s, 1H), 6.95 (s, 1H), 6.06 (s, 2H), 4.08 (t, J = 6.9 Hz, 2H), 2.89 (septet, J = 6.4 Hz, 1H), 2.57 (t, J = 7.2 Hz, 2H), 1.91 (m, 2H), 1.14 (d, J = 6.4 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 154.0, 152.1, 151.2, 149.7, 148.9, 147.5, 133.6, 132.0, 119.8, 119.1, 117.9, 115.3, 110.9, 102.1, 49.2, 42.9, 40.8, 28.3, 21.3; HRMS (ESI) m/z [M+H]+ calcd. for C21H25N8O2S, 453.1821; found 453.1819; HPLC: method A Rt = 5.60, method B Rt = 4.87.
9-(3-(Isopropylamino)propyl)-8-(6-(1-methyl-1H-pyrazol-5-yl)benzo[d][1,3]dioxol-5-ylthio)-9H-purin-6-amine (26). 1H NMR (500 MHz, CDCl3) δ 8.25 (s, 1H), 7.40 (d, J = 1.8 Hz, 1H), 7.05 (s, 1H), 6.80 (s, 1H), 6.08 (s, 2H), 6.06 (d, J = 1.8 Hz, 1H), 5.91 (br s, 2H), 4.10 (t, J = 6.7 Hz, 2H), 3.67 (s, 3H), 2.85 (septet, J = 6.3 Hz, 1H), 2.53 (t, J = 6.7 Hz, 2H), 1.97 (m, 2H), 1.13 (d, J = 6.3 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 154.4, 152.7, 151.7, 149.3, 149.0, 147.0, 140.6, 138.5, 127.7, 123.3, 120.0, 113.8, 111.7, 107.4, 102.5, 49.6, 43.2, 41.1, 37.1, 29.1, 22.0; HRMS (ESI) m/z [M+H]+ calcd. for C22H27N8O2S, 467.1978; found 467.1985; HPLC: method A Rt = 5.74, method B Rt = 5.20.
9-(3-(Isopropylamino)propyl)-8-(6-(isoxazol-4-yl)benzo[d][1,3]dioxol-5-ylthio)-9H-purin-6-amine(27). 4-Isoxazoleboronic acid pinacol ester (34.2 mg, 0.1755 mmol) was added to 1 (30 mg, 0.0585 mmol) and NaHCO3 (14.7 mg, 0.1755 mmol). DMF (1.2 mL) was added and the reaction mixture was evacuated and back filled with nitrogen. This was repeated four times then nitrogen was bubbled through the reaction mixture for 10 min. Then H2O (0.1 mL) and Pd(PPh3)2Cl2 (8 mg, 0.0117 mmol) were added and the reaction mixture was stirred at rt for 24 h. Solvent was removed under reduced pressure and the resulting residue was purified by preparatory TLC (hexane:CH2Cl2:EtOAc:MeOH-NH3 (7N), 4:7:2:1) to give 11.5 mg (43%) of 27. 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.66 (s, 1H), 8.45 (s, 1H), 8.17 (s, 1H), 7.18 (s, 1H), 7.01 (s, 1H), 6.13 (s, 2H), 4.37 (t, J = 7.0 Hz, 2H), 3.27 (septet, J = 7.1 Hz, 1H), 2.89 (t, J = 7.1 Hz, 2H), 2.22 (m, 2H), 1.38 (d, J = 6.5 Hz, 6H); MS (ESI) m/z [M+H]+ 454.1; HPLC: method A Rt = 5.87; method B Rt = 5.57.
2-(6-(6-Amino-9-(3-(isopropylamino)propyl)-9H-purin-8-ylthio)benzo[d][1,3]dioxol-5-yl)acetonitrile (28). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.17 (s, 1H), 7.14 (s, 1H), 7.12 (s, 1H), 6.10 (s, 2H), 4.35 (t, J = 6.9 Hz, 2H), 3.99 (s, 2H), 3.08 (septet, J = 6.5 Hz, 1H), 2.82 (t, J = 7.0 Hz, 2H), 2.25 (m, 2H), 1.27 (d, J = 6.5 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 154.2, 152.1, 152.0, 151.5, 150.8, 148.6, 147.7, 129.5, 119.2, 117.6, 116.2, 110.3, 102.7, 49.8, 42.5, 40.7, 27.7, 22.9, 20.4; HRMS (ESI) m/z [M+H]+ calcd. for C20H24N7O2S, 426.1712; found 426.1712; HPLC: method A Rt = 5.69, method B Rt = 4.57.
9-(3-(Isopropylamino)propyl)-8-(6-(3-methylbut-2-en-2-yl)benzo[d][1,3]dioxol-5-ylthio)-9H-purin-6-amine (29). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.22 (s, 1H), 6.80 (s, 1H), 6.62 (s, 1H), 5.99 (s, 2H), 4.24 (t, J = 6.8 Hz, 2H), 2.77 (septet, J = 6.2 Hz, 1H), 2.54 (t, J = 6.8 Hz, 2H), 2.02 (m, 2H), 1.85 (s, 3H), 1.74 (s, 3H), 1.36 (s, 3H), 1.09 (d, J = 6.3 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 154.3, 152.3, 151.3, 149.0, 148.5, 147.2, 142.3, 130.7, 128.2, 119.3, 119.1, 112.6, 110.1, 101.9, 43.2, 41.1, 29.2, 21.9, 21.8, 20.1, 19.9; HRMS (ESI) m/z [M+H]+ calcd. for C23H31N6O2S, 455.2229; found 455.2215; HPLC: method A Rt = 6.66, method B Rt = 8.07.

STILLE COUPLING
General conditions. A mixture of 1 (30 mg, 0.0585 mmol, 1 eq.), (n-Bu)3SnR (4 eq.), LiCl (2 eq.) and Pd(PPh3)4 (10-20 mol%) in DMF (1 mL) in a 10 mL RBF equipped with a magnetic stir bar and rubber septum was evacuated and back filled with nitrogen. This was repeated four times then the reaction mixture was heated under nitrogen at 90-100 °C for 18 h. Solvent was removed under reduced pressure and the resulting residue was purified by preparatory TLC to yield compounds 30-38.
8-(6-(4-(Benzyloxy)phenyl)benzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (30). 1H NMR (500 MHz, CDCl3) δ 8.28 (s, 1H), 7.47 (d, J = 7.3 Hz, 2H), 7.42 (t, J = 7.3 Hz, 2H), 7.36 (t, J = 7.1 Hz, 1H), 7.22 (d, J = 8.5 Hz, 2H), 6.93-6.98 (m, 3H), 6.84 (s, 1H), 6.02 (s, 2H), 5.79 (br s, 2H), 5.09 (s, 2H), 4.03 (t, J = 6.7 Hz, 2H), 2.73 (septet, J = 6.1 Hz, 1H), 2.44 (t, J = 6.6 Hz, 2H), 1.79-1.88 (m, 2H), 1.06 (d, J = 6.2 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 159.1, 154.9, 153.2, 152.2, 149.2, 148.4, 148.1, 139.6, 137.5, 133.4, 131.1, 129.3, 128.7, 128.2, 121.2, 120.5, 115.0, 113.7, 111.7, 102.5, 70.7, 49.6, 44.0, 41.7, 30.2, 23.1; HRMS (ESI) m/z [M+H]+ calcd. for C31H33N6O3S, 569.2335; found 569.2352.
9-(3-(Isopropylamino)propyl)-8-(6-(4-morpholinophenyl)benzo[d][1,3]dioxol-5-ylthio)-9H-purin-6-amine (31). 1H NMR (500 MHz, CDCl3) δ 8.28 (s, 1H), 7.20 (d, J = 8.4 Hz, 2H), 6.95 (s, 1H), 6.87 (d, J = 8.5 Hz, 2H), 6.84 (s, 1H), 6.01 (s, 2H), 5.81 (br s, 2H), 4.02 (t, J = 6.8 Hz, 2H), 3.85-3.92 (m, 4H), 3.16-3.24 (m, 4H), 2.71 (septet, J = 6.2 Hz, 1H), 2.43 (t, J = 6.7 Hz, 2H), 1.78-1.86 (m, 2H), 1.04 (d, J = 6.2 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 154.9, 153.2, 152.2, 151.2, 149.2, 148.4, 148.0, 139.7, 132.0, 130.8, 121.4, 120.5, 115.4, 113.6, 111.6, 102.5, 67.5, 49.56, 49.51, 44.1, 41.8, 30.3, 23.2; HRMS (ESI) m/z [M+H]+ calcd. for C28H34N7O3S, 548.2444; found 548.2454.
9-(3-(Isopropylamino)propyl)-8-(6-(pyrimidin-5-yl)benzo[d][1,3]dioxol-5-ylthio)-9H-purin-6-amine (32). 1H NMR (600 MHz, CDCl3) δ 9.07 (s, 1H), 8.68 (s, 2H), 8.17 (s, 1H), 7.07 (s, 1H), 6.82 (s, 1H), 6.05 (s, 2H), 5.45 (br s, 2H), 4.07 (t, J = 6.7 Hz, 2H), 2.68-2.77 (m, 1H), 2.45 (t, J = 6.6 Hz, 2H), 1.80-1.88 (m, 2H), 1.04 (d, J = 6.0 Hz, 6H); 13C NMR (150 MHz, CDCl3) δ 157.6, 156.7, 153.9, 152.3, 151.7, 149.9, 149.0, 147.8, 134.1, 133.4, 119.7, 119.5, 115.6, 110.8, 102.5, 49.3, 43.1, 40.9, 29.7, 22.1; HRMS (ESI) m/z [M+H]+ calcd. for C22H25N8O2S, 465.1821; found 465.1820.
9-(3-(Isopropylamino)propyl)-8-(6-(pyrazin-2-yl)benzo[d][1,3]dioxol-5-ylthio)-9H-purin-6-amine (33). 1H NMR (600 MHz, CDCl3) δ 8.79 (d, J = 1.5 Hz, 1H), 8.56 (dd, J = 1.5, 2.5 Hz, 1H), 8.46 (d, J = 2.5 Hz, 1H), 8.21 (s, 1H), 7.03 (s, 1H), 6.88 (s, 1H), 5.98 (s, 2H), 5.74 (br s, 2H), 4.05 (t, J = 7.0 Hz, 2H), 2.60 (septet, J = 6.2 Hz, 1H), 2.38 (t, J = 6.8 Hz, 2H), 1.72-1.80 (m, 2H), 0.94 (d, J = 6.2 Hz, 6H); 13C NMR (150 MHz, CDCl3) δ 154.3, 153.2, 152.8, 151.6, 149.2, 148.9, 147.2, 145.2, 143.4, 143.0, 133.9, 122.2, 119.9, 113.6, 110.4, 102.3, 48.8, 43.7, 41.4, 30.0, 22.8; HRMS (ESI) m/z [M+H]+ calcd. for C22H25N8O2S, 465.1821; found 465.1798.
9-(3-(Isopropylamino)propyl)-8-(6-(oxazol-2-yl)benzo[d][1,3]dioxol-5-ylthio)-9H-purin-6-amine (34). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.25 (s, 1H), 7.75 (s, 1H), 7.46 (s, 1H), 7.27 (s, 1H), 6.71 (s, 1H), 6.06 (s, 2H), 4.26 (t, J = 6.9 Hz, 2H), 2.75 (septet, J = 6.3 Hz, 1H), 2.53 (t, J = 6.9 Hz, 2H), 1.98 (m, 2H), 1.06 (d, J = 6.3 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 160.0, 154.7, 152.8, 151.3, 150.1, 148.5, 146.8, 139.0, 128.3, 123.7, 122.3, 120.0, 112.1, 109.7, 102.7, 43.2, 41.5, 29.3, 22.0; HRMS (ESI) m/z [M+H]+ calcd. for C21H24N7O3S, 454.1661; found 454.1650; HPLC: method A Rt = 5.77, method B Rt = 5.28.
9-(3-(Isopropylamino)propyl)-8-(6-(thiazol-2-yl)benzo[d][1,3]dioxol-5-ylthio)-9H-purin-6-amine (35). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.20 (s, 1H), 7.87 (d, J = 3.3 Hz, 1H), 7.45 (s, 1H), 7.44 (d, J = 3.3 Hz, 1H), 6.98 (s, 1H), 6.11 (s, 2H), 4.21 (t, J = 6.9 Hz, 2H), 2.78 (septet, J = 6.3 Hz, 1H), 2.55 (t, J = 6.9 Hz, 2H), 1.98 (m, 2H), 1.09 (d, J = 6.3 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 154.5, 152.5, 152.4, 151.4, 149.75, 149.69, 148.0, 142.7, 121.13, 121.07, 120.1, 119.4, 114.6, 110.9, 102.9, 43.2, 41.3, 29.2, 21.9; HRMS (ESI) m/z [M+H]+ calcd. for C21H24N7O2S2, 470.1433; found 470.1438; HPLC: method A Rt = 5.86, method B Rt = 5.66.
9-(3-(Isopropylamino)propyl)-8-(6-(1-methyl-1H-imidazol-5-yl)benzo[d][1,3]dioxol-5-ylthio)-9H-purin-6-amine (36). 1H NMR (600 MHz, CDCl3) δ 8.21 (s, 1H), 7.40 (s, 1H), 6.93 (s, 1H), 6.82 (s, 1H), 6.73 (s, 1H), 6.00 (s, 2H), 5.53 (br s, 2H), 4.04 (t, J = 6.8 Hz, 2H), 3.38 (s, 3H), 2.66 (septet, J = 6.2 Hz, 1H), 2.42 (t, J = 6.8 Hz, 2H), 1.76-1.84 (m, 2H), 0.98 (d, J = 6.2 Hz, 6H); 13C NMR (150 MHz, CDCl3) δ 153.0, 151.7, 150.6, 148.0, 147.5, 145.9, 137.2, 129.2, 128.1, 124.8, 123.6, 118.8, 112.0, 111.1, 101.2, 47.9, 42.5, 40.2, 30.8, 28.6, 21.4; HRMS (ESI) m/z [M+H]+ calcd. for C22H27N8O2S, 467.1978; found 467.1957.
8-(6-Vinylbenzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (37). 1H NMR (CDCl3, 500 MHz) δ 8.29 (s, 1H), 7.23 (dd, J = 17.3, 10.9 Hz, 1H), 7.10 (s, 1H), 6.92 (s, 1H), 5.99 (s, 2H), 5.64 (br s, 2H), 5.61 (d, J = 17.3 Hz, 1H), 5.29 (d, J = 11.0 Hz, 1H), 4.26 (t, J = 7.1 Hz, 2H), 2.73 (septet, J = 6.3 Hz, 1H), 2.57 (t, J = 6.8 Hz, 2H), 1.97 (m, 2H), 1.05 (d, J = 6.3Hz, 6H); 13C NMR (CDCl3, 125 MHz) δ 154.1, 152.6, 148.0, 133.7, 115.7, 113.6, 106.0, 101.9, 48.8, 47.2, 43.8, 41.5, 30.0, 29.7, 22.7, 19.2; MS (ESI) m/z 412.9 [M+H]+.
8-(6-Allylbenzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (38). 1H NMR (CDCl3, 500 MHz) δ 8.27 (s, 1H), 6.92 (s, 1H), 6.80 (s, 1H), 5.99 (s, 2H), 5.84-5.91 (m, 1H), 5.59 (br s, 2H), 4.98-5.07 (m, 2H), 4.28 (t, J = 6.9 Hz, 2H), 3.54 (m, 2H), 2.77 (septet, J = 6.3 Hz, 1H), 2.58 (t, J = 6.8 Hz, 2H), 1.94-2.04 (m, 2H), 1.07 (d, J = 6.3 Hz, 6H); 13C NMR (CDCl3, 125 MHz) δ 154.0, 152.4, 151.9, 147.8, 146.9, 136.9, 136.2, 119.5, 116.6, 113.9, 110.3, 101.7, 48.9, 43.5, 41.2, 38.3, 29.7, 22.5; MS (ESI) m/z 426.8 [M+H]+.

HECK COUPLING
General conditions. A solution of 1 (30 mg, 0.0585 mmol, 1 eq.) in NMP (1.5 mL) in a 10 mL RBF equipped with a magnetic stir bar and rubber septum was evacuated and back filled with nitrogen. This was repeated four times, then N,N-diisopropylethylamine (1.2-2 eq.), alkene (1.1-20 eq.) and Pd(PPh3)4 (10-20 mol%) were added and the reaction mixture was heated under nitrogen at 55-100 °C for 20-24 h. Solvent was removed under reduced pressure and the resulting residue was purified by preparatory TLC to yield compounds 39-43. 44 was similarly prepared and obtained following Boc removal as is described below.
(E)-Methyl-3-(6-(6-amino-9-(3-(isopropylamino)propyl)-9H-purin-8-ylthio)benzo[d][1,3]dioxol-5-yl)acrylate (39). 1H NMR (500 MHz, CDCl3) δ 8.24 (s, 1H), 8.17 (d, J = 15.8 Hz, 1H), 7.14 (s, 1H), 7.03 (s, 1H), 6.27 (d, J = 15.8 Hz, 1H), 6.05 (s, 2H), 5.66 (br s, 2H), 4.37 (t, J = 6.4 Hz, 2H), 3.77 (s, 3H), 2.99-3.08 (m, 1H), 2.73 (t, J = 6.5 Hz, 2H), 2.27-2.33 (m, 2H), 1.27 (d, J = 6.1 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 167.0, 154.2, 152.5, 151.7, 149.9, 149.7, 147.0, 141.1, 131.6, 123.3, 119.8, 119.0, 114.5, 106.6, 102.4, 51.9, 49.4, 43.2, 41.1, 31.9, 22.7; HRMS (ESI) m/z [M+H]+ calcd. for C22H27N6O4S, 471.1815; found 471.1808; HPLC: method A Rt = 6.07, method B Rt = 6.39.
(E)-3-(6-(6-Amino-9-(3-(isopropylamino)propyl)-9H-purin-8-ylthio)benzo[d][1,3]dioxol-5-yl)-acrylonitrile (40). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.18 (s, 1H), 7.94 (d, J = 16.5 Hz, 1H), 7.19 (s, 1H), 7.08 (s, 1H), 6.12 (s, 2H), 5.86 (d, J = 16.5 Hz, 1H), 4.30 (t, J = 6.4 Hz, 2H), 2.88 (m, 1H), 2.68 (t, J = 6.7 Hz, 2H), 2.27-2.33 (m, 2H), 1.14 (d, J = 6.1 Hz, 6H); HRMS (ESI) m/z [M+H]+ calcd. for C21H24N7O2S, 438.1712; found 438.1725; HPLC: method A Rt = 5.83, method B Rt = 5.64.
8-(6-(Cyclopent-2-enyl)benzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (41). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.16 (s, 1H), 6.99 (s, 1H), 6.82 (s, 1H), 6.01 (s, 2H), 5.98 (m, 1H), 5.63 (m, 1H), 4.41 (t, J = 6.4 Hz, 2H), 3.39 (m, 1H), 3.34 (septet, J = 6.6 Hz, 1H), 2.95 (t, J = 6.4 Hz, 2H), 2.22-2.52 (m, 5H), 1.50-1.59 (m, 1H), 1.44 (d, J = 6.6 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 154.3, 151.9, 151.5, 150.7, 149.9, 147.0, 145.6, 133.4, 129.8, 119.1, 116.0, 115.2, 108.5, 102.1, 50.9, 42.2, 41.9, 40.5, 39.9, 29.9, 26.9, 19.6; HRMS (ESI) m/z [M+H]+ calcd. for C23H29N6O2S, 453.2073; found 453.2064; HPLC: method A Rt = 6.51, method B Rt = 7.79.
8-(6-(2,3-Dihydrofuran-3-yl)benzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (42). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.18 (s, 1H), 7.02 (s, 1H), 7.00 (s, 1H), 6.55 (m, 1H), 6.04 (s, 2H), 4.99 (m, 1H), 4.64-4.69 (m, 1H), 4.45 (m, 1H), 4.31 (t, J = 6.8 Hz, 2H), 4.05 (dd, J = 6.2, 9.2 Hz, 1H), 3.40 (m, 1H), 2.67 (t, J = 6.4 Hz, 2H), 2.14 (m, 2H), 1.16 (d, J = 6.1 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 153.8, 152.4, 152.0, 150.2, 148.1, 147.4, 146.9, 142.6, 119.7, 117.6, 114.5, 108.6, 104.0, 101.9, *, 48.9, 45.3, 43.7, 41.3, 30.0, 22.8, *signal overlaps with solvent; 13C NMR (125 MHz, CD2Cl2) δ 154.4, 152.64, 152.61, 150.7, 148.8, 147.9, 147.4, 143.3, 120.2, 118.3, 115.0, 109.0, 104.4, 102.6, 77.6, 49.7, 45.8, 43.9, 41.7, 30.2, 22.6; HRMS (ESI) m/z [M+H]+ calcd. for C22H27N6O3S, 455.1865; found 455.1862; HPLC: method A Rt = 6.04, method B Rt = 6.32.
8-(6-(2,3-Dihydrofuran-2-yl)benzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (43). 1H NMR (500 MHz, CDCl3) δ 8.23 (s, 1H), 7.06 (s, 1H), 6.96 (s, 1H), 6.43 (m, 1H), 6.01 (s, 2H), 5.94 (dd, J = 8.1, 10.8 Hz, 1H), 5.72 (br s, 2H), 4.93 (m, 1H), 4.35 (t, J = 6.8 Hz, 2H), 2.95-3.55 (m, 2H), 2.70 (t, J = 6.5 Hz, 2H), 2.39-2.47 (m, 1H), 2.22 (m, 2H), 1.25 (d, J = 6.2 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 154.1, 152.1, 151.8, 150.0, 147.8, 147.6, 145.1, 141.3, 119.5, 116.3, 114.5, 106.9, 102.0, 99.3, 79.7, 50.1, 42.4, 40.6, 37.9, 29.7, 20.9; HRMS (ESI) m/z [M+H]+ calcd. for C22H27N6O3S, 455.1865; found 455.1865; HPLC: method A Rt = 6.07, method B Rt = 6.49.
8-(6-(2,5-Dihydro-1H-pyrrol-2-yl)benzo[d][1,3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (44). A solution of 1 (30 mg, 0.0585 mmol) and N-Boc-2,3-dihydro-1H-pyrrole (19.8 mg, 20.2 µL, 0.117 mmol) in NMP (1.5 mL) was evacuated and back filled with nitrogen. This was repeated four times, then N,N-diisopropylethylamine (15.1 mg, 21 µL, 0.117 mmol) and Pd(PPh3)4 (13.5 mg, 0.0117 mmol) were added and the reaction mixture was heated under nitrogen at 100 °C for 20 h. Solvent was removed under reduced pressure and the resulting residue was purified by preparatory TLC (CH2Cl2:MeOH-NH3 (7N), 15:1) and the resulting residue was dissolved into 2 mL of CH2Cl2:TFA (4:1) and stirred for 1 h. Solvent was removed under reduced pressure and the resulting residue was purified by preparatory TLC (CH2Cl2:MeOH-NH3 (7N), 10:1) to give 6.0 mg (23%) of 44. 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.19 (s, 1H), 6.98 (s, 2H), 6.04 (m, 1H), 6.01 (s, 2H), 5.74 (m, 1H), 5.62 (d, J = 2.0 Hz, 1H), 4.31 (t, J = 6.9 Hz, 2H), 3.81-3.88 (m, 1H), 3.89-3.95 (m, 1H), 2.87 (septet, J = 6.3 Hz, 1H), 2.68 (t, J = 6.7 Hz, 2H), 2.14 (m, 2H), 1.15 (d, J = 6.3 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 154.0, 152.0, 151.7, 150.7, 149.4, 147.8, 142.8, 131.0, 129.8, 119.2, 116.8, 115.3, 108.7, 102.2, 66.1, 53.6, 43.4, 41.2, 40.4, 29.8, 22.2; HRMS (ESI) m/z [M+H]+ calcd. for C22H28N7O2S, 454.2025; found 454.2046; HPLC: method A Rt = 5.27, method B Rt = 2.72.

SONOGASHIRA COUPLING
General conditions. To a solution of 1 (20 mg, 0.039 mmol, 1 eq.) in DMF (2 mL) in a sealed tube flushed with argon was added CuI (0.5 eq.), PdCl2(PPh3)2 (15 mol%), alkyne (2-2.5 eq.) and triethylamine (5 eq.). The reaction mixture was heated at 90-100 °C for 24 h. Solvent was removed under reduced pressure and the resulting residue was purified by preparatory TLC to yield compounds 46-50. 45 was similarly prepared and obtained following trimethylsilyl removal as is described below.
8-(6-Ethynyl-benzo[1,3]dioxol-5-ylsulfanyl)-9-(3-isopropylamino-propyl)-9H-purin-6-ylamine (45). To a solution of 1 (20 mg, 0.039 mmol) in 2 ml of DMF in a sealed tube, was added CuI (3.8 mg, 0.019 mmol), PdCl2(PPh3)2 (4.2 mg, 0.006 mmol), trimethylsilylacetylene (14 µL, 0.098 mmol) and triethylamine (13.7 µL, 0.1866 mmol). The reaction mixture was heated at 90 °C for 24 h. The reaction mixture was concentrated under reduced pressure to give a white solid to which was added MeOH (1 mL) and KOH (10 mg) and was stirred at rt for 2 h. Solvent was removed under reduced pressure and the resulting residue was purified by preparatory TLC (CH2Cl2: n-hexane: EtOAc: MeOH-NH3 (7N), 4:4:2:1) to give 11 mg (69%) of 45. 1H NMR (500 MHz, CDCl3) δ 8.32 (s, 1H), 6.99 (s, 1H), 6.84 (s, 1H), 6.00 (s, 2H), 5.61 (br s, 2H), 4.31 (t, J = 7 Hz, 2H), 3.31 (s, 1H), 2.71 (m, 1H), 2.56 (t, J = 7 Hz, 2H), 1.97 (m, 2H), 1.02 (d, J = 6.5 Hz, 6H); HRMS (ESI) m/z [M+H]+ calcd. for C20H23N6O2S, 411.1603; found 411.1605.
8-((6-(Hex-1-yn-1-yl)benzo[d][1,3]dioxol-5-yl)thio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (46). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.23 (s, 1H), 6.81 (s, 1H), 6.68 (s, 1H), 5.87 (s, 2H), 4.24 (t, J = 6.9 Hz, 2H), 2.66 (septet, J = 6.2 Hz, 1H), 2.48 (t, J = 6.2 Hz, 2H), 2.31 (t, J = 6.9 Hz, 2H), 1.90 (quintet, J = 7.6 Hz, 2H), 1.44 (quintet, J = 6.2 Hz, 2H), 1.34 (sextet, J = 7.6 Hz, 2H), 0.98 (d, J = 6.2 Hz, 6H), 0.82 (t, J = 7.6 Hz, 3H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 154.4, 152.8, 151.6, 148.1, 147.9, 146.6, 127.8, 119.8, 114.8, 112.5, 111.4, 101.9, 96.1, 77.9, 48.8, 43.6, 41.5, 30.6, 29.9, 22.6, 21.9, 19.3, 13.6; HRMS (ESI) m/z [M+H]+ calcd. for C24H31N6O2S, 467.2229; found 467.2227.
8-[6-(3,3-Dimethylbut-1-ynyl)benzo[1,3]dioxol-5-ylsulfanyl]-9-(3-isopropylamino-propyl)-9H-purin-6-ylamine (47). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.25 (s, 1H), 6.99 (s, 1H), 6.97 (s, 1H), 6.05 (s, 2H), 4.41 (t, J = 7 Hz, 2H), 3.29 (m, 1H), 2.98 (t, J = 7.5 Hz, 2H), 2.24 (m, 2H), 1.34 (d, J = 6.5 Hz, 6H), 1.18 (s, 9H); HRMS (ESI) m/z [M+H]+ calcd. for C24H31N6O2S, 467.2229; found 467.2233.
8-((6-(Cyclopentylethynyl)benzo[d][1,3]dioxol-5-yl)thio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (48). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.16 (s, 1H), 6.85 (s, 1H), 6.76 (s, 1H), 5.92 (s, 2H), 4.27 (t, J = 6.2 Hz, 2H), 2.81 (septet, J = 6.9 Hz, 1H), 2.69 (quintet, J = 6.9 Hz, 1H), 2.56 (t, J = 6.2 Hz, 2H), 2.03 (quintet, J = 6.2 Hz, 2H), 1.79-1.85 (m, 2H), 1.60-1.63 (m, 2H), 1.48-1.53 (m, 4H), 1.09 (d, J = 6.2 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 154.5, 152.5, 151.5, 148.6, 148.2, 147.6, 124.2, 121.2, 119.5, 112.7, 112.5, 102.2, 100.5, 77.7, 49.7, 42.8, 41.1, 33.9, 30.9, 28.8, 25.1, 21.4; HRMS (ESI) m/z [M+H]+ calcd. for C25H31N6O2S, 479.2229; found 479.2235.
8-((6-(Cyclohexylethynyl)benzo[d][1,3]dioxol-5-yl)thio)-9-(3-(isopropylamino)propyl)-9H-purin-6-amine (49). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.13 (s, 1H), 6.87 (s, 1H), 6.78 (s, 1H), 5.94 (s, 2H), 4.29 (t, J = 6.9 Hz, 2H), 2.98 (septet, J = 6.6 Hz, 1H), 2.66 (t, J = 6.6 Hz, 2H), 2.48 (quintet, J = 4.6 Hz, 1H), 2.11 (quintet, J = 6.6 Hz, 2H), 1.57-1.67 (m, 4H), 1.30-1.36 (m, 2H), 1.22-1.26 (m, 2H), 1.19 (d, J = 5.9 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 154.5, 152.6, 151.6, 148.1, 148.0, 146.8, 125.4, 119.9, 112.5, 111.3, 101.9, 101.8, 100.2, 77.9, 49.6, 42.8, 41.1, 33.6, 32.5, 29.7, 25.9, 25.1, 24.7; HRMS (ESI) m/z [M+H]+ calcd. for C26H33N6O2S, 493.2386; found 493.2381.
9-(3-Isopropylaminopropyl)-8-(6-phenylethynylbenzo[1,3]dixool-5-ylsulfanyl)-9H-purin-6-ylamine (50). 1H NMR (500 MHz, CDCl3/MeOH-d4) δ 8.2 (s, 1H), 7.30-7.40 (m, 5H), 7.08 (s, 1H), 6.96 (s, 1H), 6.06 (s, 2H), 4.27 (m, 2H), 2.69 (m, 1H), 2.51 (m, 2H), 1.97 (m, 2H), 1.01 (d, J = 6.5 Hz, 6H); 13C NMR (125 MHz, CDCl3/MeOH-d4) δ 154.3, 152.3, 151.1, 148.8, 147.3, 131.3, 128.7, 128.3, 124.4, 122.4, 120.4, 119.3, 112.9, 112.4,102.3, 94.2, 86.6, 50.5, 43.1, 41.3, 29.2, 21.7; HRMS (ESI) m/z [M+H]+ calcd. for C26H27N6O2S, 487.1903; found 487.1913.

ACKNOWLEDGEMENTS
T.T. is funded by Susan G. Komen for the Cure (KG091313) and the Department of Defense, Breast Cancer Research Program (PDF-BC093421) and H.P. and W.S. by the National Institutes of Health grants 1U01AG032969, 1R01CA155226 and 1R21AI090501. We also thank Dr. George Sukenick and Dr. Hui Liu of the NMR Analytical Core Facility at MSKCC for expert mass spectral analysis.

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