HETEROCYCLES

■ Reaction of 5-Acetonyl-6-chloropyrimidines with Hydrazines and Diamines

Heinz Wolfers, Udo Kraatz, and Friedheim Korte*

*Lehrstuhl für Ökologische Chemie, Technische Universität München, Lichtenbergstrasse 4, D-85747 Garching, Germany

Abstract

The reaction of 5-acetonyl-6-chloro-4-ethyl-2-phenylpyrimidine (4) with hydrazines yields dihydropyrimido[4,5-c]pyridazines, while l,2-diamines give pyrrolo[2,3-d]pyrimidines and no pyrimido[4,5-e]-l, 4-diazocines. Only l,2-dimethylaminoethane reacts with 4 to give the pyrimido[4,5-e]-1,4-diazocine-system.

■ Reaction of Dimethylvinylidenecarbene with Azobenzene. A Novel Formation of Benzimidazole Derivatibe

Tadashi Sasaki,* Shoji Eguchi, and Tetsuo Ogawa

*Institute of Applied Organic Chemistry, Faculty of Engineering, Nagoya University, Chikusa, Nagoya, Aichi 464-8601, Japan

Abstract

Dimethylvinylidenecarbene (2) generated from 3-chloro-3-methyl-1-butyne (1) and alkali by the phase-transfer method reacted with azobenzene (4) to afford 1-phenyl-2-isobutenylbenzimidazole (5).

■ The Total Synthesis of Akuammicine and 16-Epi-stemmadenine. The Absolute Configuration of Stemmademine

James P. Kutney* and George B. Fuller

*Department of Chemisry, University of British Columbia, Vancouver 8, V5T 1W5, Canada

Abstract

A synthetic route leading to akuammicine (VI) and 16-epi-stemmadenine (XI) is presented. The synthesis employs Wieland-Gumlich aldehyde (III), a well-known degradation product of strych-nine (II), as a starting material. Introduction of functionality at C₁₆ in the intermediate VIIl is done in a stereochemically unambiguous fashion thereby allowing direct comparison of the synthetic substances with the natural stemmadenine series. In this manner the complete absolute configuration of stemmadenine (I) is derived.

■ Studies on the Synthesis of Bisindole Alkaloids. The Synthesis, Structure and Absolute Configuration of 18’-Epi-4’-deoxo-4’-epivinblastine, 18’-Decarbomethoxy-18’-epi-4’-epivinblastine and 18’-Epi-3’,4’-dehydrovinblastine

James P. Kutney,* James Cook, Kaoru Fuji, Adi M. Treasurywala, Jon Clardy, Jose Fayos, and Hal Wright

*Department of Chemisry, University of British Columbia, Vancouver 8, V5T 1W5, Canada

Abstract

Studies on the syntheses of 18’-epi-4’-deoxo-4’-epivinblastine (III), 18’-epi-3’,4’-dehydrovinblastine (III, 3’,4’-double bond) and 18’-decarbomethoxy-l8’-epi-4’-deaxo-4’-epivinblastine (V) are described. Particular emphasis is placed on the stereochemistry of the coupling reaction involving chloroindolenine derivatives of the cleavamine series with vindoline under acidic conditions. X-ray analyses on III and V provide the complete structures, including absolute configuration. These studies reveal that the chloroindolenine approach provides products bearing the unnatural configuration at C_18’.

■ Dealkylation of 1-sec-Alkyl-6-carbamoyl(or cyano)-3-methyluracils under Acidic Conditions

Shigeo Senda,* Kosaku Hirota, and Tetsuji Asao

*Gifu Pharmaceutical University, 6-1 Mitahora-higashi 5-chome, Gifu 502-8585, Japan

Abstract

Hydrolysis of 1-sec-alkyl-6-carbamoyl-3-methyluracils in refluxing 48% hydrobromic acid causes dealkylation at the 1-position to give 3-methylorotic acid. Treatment of 1-sec-alkyl-6-carbamoyl(or cyano)-3-methyluracils in 98% H₂SO₄ afford 1-dealkylated 6-carbamoyl-1-methyluracils.

■ Synthesis and Reactions of 2-Aryl-1,3-oxathiolium Salts

Kentaro Hirai* and Teruyuki Ishiba

*Shionogi Research Laboratories, Shionogi & Co. Ltd., Fukushima-ku, Osaka 553-0002, Japan

Abstract

A convenient method for the preparation of 2-aryl-1,3-oxathiolium salts and their conversion into thiophene derivatives are described.

■ β-Carboline Alkaloids

Kenneth Stuart* and Rex Woo-Ming

*Department of Chemsitry, University of the West Indies, Mona, Kingston 7, Jamaica

■ Studies on Chinese Drugs in Taiwan

Hong-Yen Hsu* and Yuh-Pan Chen

*Brion Research Institute of Taiwan, 116, Chung-Ching South Rd. Sec. 3, Taipei, Taiwan, R.O.C.

Abstract

The major studies on the chemical constituents relating to 28 kinds of Chinese herbs and 12 kinds of folk medicines used in Taiwan are collected in this review. From those plants, 41 new constituents were isolated and their structures were determined during the period from 1968 to 1974.