Total syntheses of (.+-.)-physovenine and (.+-.)-physostigmine. An application of tandem electrocyclic-[3, 3] sigmatropic reaction of benzocyclobutenes

K Shishido, E Shitara, H Komatsu…

Index: Shishido; Shitara; Komatsu; et al. Journal of Organic Chemistry, 1986 ,  vol. 51,  # 15  p. 3007 - 3011

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Citation Number: 40

Abstract

A high yield (40% overall yield) 14step synthesis of (&)-physovenine and a formal synthesh of (&)-physostigmine, as applications of the tandem electrocyclic-[3, 3] sigmatropic reaction of benzocyclobutenes, are described. The thermolysis of the benzocyclobutenyl allyl ester 6 givea quantitatively the isochromanone 7, which can be elaborated to the key oxindole intermediate 8 in a seven-step sequence.(&)-Physovenine is obtained from 8 through a ...