Total synthesis of optically active costaclavine (synthetic studies of indoles and related compounds part 48.)

Abstract

The first total synthesis of optically active costaclavine (18), an ergot alkaloid, was accomplished starting from methyl [4R-(Z)]-[4-[[(1,1- dimethylethoxy)carbonyl]methylamino]-3,4-dihydro-1-[(4- methylphenyl)sulfonyl]benz[cd]indol-5(1H)-ylidene]acetate (8), which was prepared by intramolecular cyclization of 1,1-dimethylethyl [1R-(E)]-[1-[[4- bromo-l-[(4-methylphenyl)-sulfonyl]-1H-indol-3-yl]methyl]-4-carbomethoxy-2- propenyl] methylcarbamate (7) according to the method we developed earlier during the course of the total synthesis of chanoclavine-I (9).