139115-76-7Relevant articles and documents
Rapid Syntheses of Some Indole Alkaloids of the Calabar Bean
Horne, Stephen,Taylor, Nicholas,Collins, Scott,Rodrigo, Russell
, p. 3047 - 3052 (2007/10/02)
A rapid, efficient route to 3,3-disubstituted oxindoles from o-iodo anilines has been developed.It involves the cyclisation of the corresponding fumarate amides 4 and 15 with butyllithium at -100 deg C in the presence of an excess of trimethylchlorosilane.An X-ray crystal structure of 4 suggests that the speed and efficiency of this intramolecular Michael addition is dependent on the conformation adopted by 4 which is particularly suitable for the reaction.This method has been applied to the synthesis of the alkaloids physovenine, physostigmine and esermethole in very high overall yields.