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Paper | Regular issue | Vol 53, No. 4, 2000, pp.821-830
Published online, 1st January, 1970
DOI: 10.3987/COM-99-8820
Stereochemical Aspects during Addition Reaction of 2-Cyano-1,2-dihydroisoquinolines with Bromine in Methanol with and without Pyridine

Michiharu Sugiura,* Koosuke Asai, Keiichiro Hatano, Yukihisa Kurono, and Yoshiki Hamada

*Faculty of Pharmacy, Meijo University, Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan

Abstract

2-Cyano-1-methoxy-1,2-dihydroisoquinoline (3) treated with bromine in methanol gave 4-bromo-2-cyano-1,3-dimethoxy-1,2,3,4-tetrahydroisoquinolines (4) exhibiting two configurational isomers (4a and 4b). During repeated recrystallization of 4a, auto-hydrolysis led it to 1-demethylation product (6), whereas 4b was intact giving single crystals. The structures of 4b and 6a were determined by X-Ray crystallography. 2-Cyano-1-hydroxy-1,2-dihydroisoquinoline (7) treated with bromine in methanol containing pyridine gave 6a stereoselectively in high yield, whereas from 3 compounds (4a) and (4b) were afforded in a product ratio of 1 : 1. The mechanisms for the 4a and 4b interconvertible reaction and also for the reaction from 7 to 6a were examined.