A concise route to racemic anatoxin a from cycloocta-1,5-diene

Abstract

The synthesis of racemic anatoxin a (1a) from cycloocta-1,5-diene via its 1:1 cycloadduct with N-chlorosulfonyl isocyanate is described. The N-unsubstituted beta-lactam 2b was converted to a beta-amino ester 3 which was then submitted to a Pd-catalyzed cyclization to afford the conjugated ester 4a. The N-tosyl derivative 4b was then elaborated into N-tosylanatoxin a (1b) via a Weinreb amide.