HETEROCYCLES

■ A Biomimetic Approach to Benzophenanthridine Alkaloid from Protoberberine Alkaloid

Tetsuji Kametani,* Makoto Takemura, Masataka Ihara, Keiichiro Fukumoto, and Keiichi Takahashi

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

Abstract

10-Hydroxy-2,3,11-trimethoxyberbine (5) is transformed along by a biogenetic pattern into 7,8-dihydro-10-hydroxy-2,3,11-trimethoxybenzophenanthridine (11) via the methine base (6).

■ Synthesis of a New Ring System: 1,2,4-Oxadiazol[2,3-a]pyrimidin-4-one

Nicolò Vivona* and Giuseppe Cusmano

*Instituto de Chimica Organica, Facolta de Scienze, Università digli Studi di Palermo, 20 via Archirafi 90123 Palermo, Italy

Abstract

The preparation of 2,7-diphenyl-1,2,4-oxadiazol[2,3-a]pyrimidin-4-one is described and its ring opening by hydrogenation and hydrolysis examined.

■ Photochemical Ring-contraction Reactions of Benz[d]-3,1-oxazepines Having No Substituent at the 5-Position to Indole-3-carboxaldehydes

Chikara Kaneko* and Reiko Kitamura

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

Abstract

Irradiation of 5-unsubstituted benz[d]-3,1-oxazepines having phenyl or cyano group at the 2-position with high-pressure mercury lamp without filter resulted in the formation of 2-phenyl- or 2-cyanoindole-3-carboxaldehydes in good yields. The corresponding quinoline 1-oxides can directly be converted to the indole-3-carboxaldehydes by irradiation (254 nm. rays) in acetonitrile without isolating the oxazepines.

■ Photochemical Ring Contraction Reactions of Quinline 1-Oxides Having Carboxylic Acid Function at the 4-Position to Indole-3-carboxaldehydes via the Corresponding Oxazepines

Chikara Kaneko* and Reiko Kitamura

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

Abstract

Irradiation of the N-oxide of 2-methyl- or 2-phenylquinoline 4-carboxylic acid with high-pressure mercury lamp with Pyrex filter in methanol was found to give 2-substituted indole-3-carboxaldehyde in an appreciable amount, together with carbostyril derivatives. In order to account for the formation of these indoles a plausible mechanism including benz[d]-3,1-oxazepines and 3-formyl-3H-indole-3-carboxylic acids is proposed. It was verified that the N-oxide of quinoline 4-carboxylic acid also gave indole-3-carboxaldehyde under these conditions.

■ Reductive Cyclization of 3-(o-Nitrobenzylidene)-2,4-dioxopentanoic Acid and Its Ester

Takushi Kurihara,* Yukito Ohshita, and Yasuhiko Sakamoto

*Faculty of Pharmaceutical Science, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan

Abstract

Catalytic reduction of 3-(o-nitrobenzy1idene)-2,4-dioxopentanoic acid (1) and its methyl ester (2) in methanol gave 2-methyl-3-(α-hydroxy)quinolineacetic acid 1-oxide (3), and methyl 1,4-dihydro-1-hydroxy-4-methoxy-2-methyl-3-quinolineglyoxylate (8) in 88% and 91% yields, respectively.

■ A New Stereoselective Synthesis of (±)-Deoxyaspidodispermine

Yasushi Honma and Yoshio Ban*

*Faculty of Pharmaceutical Sciences, Toho University, 2-2-1, Miyama, Funabashi, Chiba 274-8510, Japan

Abstract

A new stereoselective total synthesis of (±)-deoxyaspidodispermine (I) was achieved; the feature of the present synthesis was to involve the photosensitized oxygenation of the diene (V) by singlet oxygen, exclusively furnishing the cyclic peroxide adduct (VI) of 6-orientation, which might be regarded as a biomimetic process subsequent to Djerassi’s work on the removal of the angular ethyl group of Aspidosperma alkaloids.

■ The Reaction of 1,2-Diamines with a 2,3-Dioxopyrrolidines as an Approach to Pyrrolo[2,3-b]pyrazines

Stewart W. Schneller* and Jung-Hui Sun

*Department of Chemistry, University of South Florida, Tampa, Florida 33620, U.S.A.

Abstract

The reaction of 1-benzyl-2,3-dioxopyrrolidine with aromatic dimnines as a means of preparing polycyclic molecules containing the pyrrolo[2,3-b]pyrazine moiety has been studied as a model route to molecules isomeric with the biologically active pyrrolo[2,3-d]pyrimidines. The spiro derivatives 17-19, however, have been the realized products rather than the desired linear systems (e.g., 9).

■ A Review on the Photochemistry of 2H-Azirines

Paul Gilgen, Heinz Heimgartner, Hans Schmid,* and Hans-Jürgen Hansen

*Organisch-chemisches Institut, Universität, Rämistrasse 76, CH-8001 Zürich, Switzerland