HETEROCYCLES

■ Photochemical Synthesis of 2-Phenylpyrroles by the Cyclization of β-Aminovinyl Ketones

Takehiko Nishio and Yoshimori Omote*

*Department of Chemistry, University of Tsukuba, 1-1-1 Ten-nodai, Tsukuba-shi, Ibaraki, 305-8571, Japan

Abstract

On irradiation, β-aminovinyl phenyl ketones (1) having such substituents as CH₃, OCH₃, and Cl on the phenyl ring cyclize to give pyrrole derivatives (2), except β-aminovinyl ρ-biphenyl ketone (1h). Also exocyclic β-aminovinyl ketone (3 and 4) are inert. The photochemical behavior of (1) is discussed in relation with that of aryl alkyl ketone.

■ New Thiapyridinophanes

Otohiko Tsuge* and Masahiro Okumura

*Research Institute of Industrial Science, Faculty of Engineering, Kyushu University, 6-1, Kasuga-koen, Kasuga 816-8580, Japan

Abstract

Syntheses, some spectral and chemical properties of new 18-membered trithiapyridinophane 1 and 13-membered dithiapyridinophane 2 are described.

■ The Structure of Alkylation Products of 2-Substituted 3-Methylbenzolines with Meerwein Reagents

kin-ya Akiba,* Yoshio Ohara, and Naoki Inamoto

*Department of Chemistry, Scool of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033

Abstract

Methylation and ethylation of 2-substituted 3-methylbenzothiazolines with Meerwein reagents gave the corresponding ammonium fluoroborates. The configuration of two methyl groups on nitrogen was assigned, i. e., one at lower field (in NMR) is syn to 2-C-H and the other at higher field is syn to 2-C-R.

■ Picrohelein, a New Cytotoxic and Bitter Pseudoguaianolide from Sendai Helenium autumnale L

Yoshikazu Kondo,* Tsuyoshi Tomimori, Norio Hiraga, and Tsunematsu Takemoto

*Pharmaceutical Institute, Tohoku University, Aobayama, Sendai 980-8578, Japan

Abstract

Picrohelenin, a cytotoxic and intensely bitter pseudoguaianolide from the epigeal parts of Sendai Helenium autunnale L. (Compositae) has been established to be the structure I. The taste threshold of picrohelenin in man is 1.92 x 10^-7 - 3.7 x 10^-7 M. Picrohelenin proved to be inhibitory to tissue culture HeLa cells and its ID₅₀ was 1.5 μg/ml.

■ Oxidative Cyclization of 6-(N-Alkylanilino)-5-aminouracils to Flavins with Diethyl Azodicarboxylate or Nitrosobenzene

Fumio Yoneda* and Yoshiharu Sakuma

*Faculty of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-hon-machi, Kumamoto 862-0973, Japan

Abstract

Treatment of 6-(N-alkylanilino)-5-aminouracils with diethyl azodicarboxylate or nitrosobenzene in ethanol or acetic acid in the indirect sunshine gave the correspond- ing flavins. The reaction mechanism has been definitely shown by the isolation of the key intermediates, 6-(N-alkylanilino)-5-iminouracils.

■ Syntheses of Thieno[2,3-c]-, Pyrrolo[2,3-c]- and Indolo[2,3-c]diazanaphthalenes by Photocyclization of Acylaminopyridines

Yuichi Kanaoka,* Kunio San-nohe, Yasumaru Hatanaka, Kazuhiko Itoh, Minoru Machida, and Masanao Terashima

*Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan

Abstract

By the photocyclization of the amides derived from thiophene-2-, N-methylpyrrole-2-, and N-methylindole-2-carboxylic acids and aminopyridines, novel polycyclic heteroaromatic systems such as thieno[2,3-c]-, pyrrolo[2,3-c]-, and indolo[2,3-c]diazanaphthalenes were synthesized.

■ Reaction of Benzofuran with Indine Azide: Formation of cis- and trans-2,3-Diazido-2,3-dihydrobenzofurans

Sundo Kwon, Tomoko Okada, Masazumi Ikeda, and Yasumitsu Tamura*

*Faculty of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Toyonaka, Osaka 560-0043, Japan

Abstract

Benzofuran reacted with IN₃ to give in good yields cis- and trans-2,3-diazido-2,3-dihydrobenzofurans, both of which were readily converted to 3-azidobenzofuran.

■ A Facile Formation of Benzo[a]quinolizin-4-ones

Tetsuji Kametani,* Hirofumi Terasawa, Masataka Ihara, and Keiichiro Fukumoto

*Pharmaceutical Institute, Tohoku University, Aobayama, Sendai 980-8578, Japan

Abstract

Reaction of 3,4-dihydro-6,7-dimethoxy-1-methylisoquinoline (1) with diethyl α,γ-diethoxycarbonylglutaconate (2) in ethanol, followed by silica gel chromatography, gave 3-ethoxycarbonyl-6,7-dihydro-9,10-dimethoxybenzo[a]quinolizin-4-one (4). On the other hand, the above same reaction, followed by reduction with sodium borohydride, yielded 3-ethoxycarbonyl-2-diethoxycarbonylmethyl-1,2,3,6,7,11b-hexahydro-9,10-dimethoxybenzo[a]quinolizin-4-one (7). Hydrolysis of 4 and 7 with ethanolic potassium hydroxide furnished the same acid (6).

■ A Versatile Synthesis of Reissert Compounds

Somsak Ruchirawat,* Niramon Phadungkul, Mayuree Chuankamnerdkarn, and Chachanat Thebtaranonth

*Department of Chemistry, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand

Abstract

Reissert compounds were prepared by the reaction of heterocyclic base with acid chloride and trimethylsilyl cyanide in methylene chloride.

■ Reissert Compound Studies. XXVIII. A Novel Cyanohydrin Formation

Raymond F. Watts and Frank D. Popp*

*Department of Chemistry, University of Missouri-Kansas City, Kansas City, Missouri 64110, U.S.A.

Abstract

Reaction of the anion of 1-benzoyl-l,2-dihydroisoquinaldonitrile with 3-ethyl-1,3,4,6,7,11b-hexahydro-9,10-dimethoxybenzo(a)quinolizin-2-one gives the ketone cyanohydrin.

■ Chemistry of the 6,8-Dioxabicyclo[3.2.1]octane Series. Sources, Synthesis, Structures and Reactions

Bradford P. Mundy,* Kenneth B. Lipkowitz, and Gary W. Dirks

*Department of Chemistry, Montana State University, Bozeman, Montana 59717, U.S.A.