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Paper | Regular issue | Vol 26, No. 5, 1987, pp.1271-1275
Published online, 1st January, 1970
DOI: 10.3987/R-1987-05-1271
Reactions of (-)-Physositigmine and (-)-N-Methyphysostigmine in Refluxing Butanol and at High Temperature: Facile Preparation of (-)-Eseroline

Qian-Sheng Yu, Bernhard Schönenberger, and Arnold Brossi

*Section of Medical Chemistry, Laboratory of Analytical Chemistry, NIDDK, National Institute of Health, Bethesda, MD 20982, U.S.A.


(-)-Physostigmine (1), when refluxed in 1-butanol in the presence of sodium butylate afforded (-)-eseroline (3) in high yield, isolated as fumarate salt. Butyl N-methylearbamate (4) was obtained from the mother liquor. (-)-N-Methylphysostigmine (2), prepared from 3 and dimethylearbamoyl chloride, underwent under these conditions, similar decomposition suggesting that formation of 3 from 1 and 2 is the result of a nucleophilic substitution. Subliming, or distilling 1, in high vacuum afforded (-)-eseroline (2) and methyl isocyanate trapped by 1-butanol as butyl N-methylcarbamate (4). Compound 3distilled without decomposition. It is suggested that pyrolysis of 1, therefore, proceeds by fragmentation, forming N-methylisocyanate and (-)-eseroline (3) as reaction products.