A fully regiocontrolled synthesis of desacetamidoisocolchicine: Formal total synthesis of colchicine

Abstract

The tetracyclic compound 3a, which has been synthesised in nine steps from the known cyclohexenone 6, reacts with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) to give desacetamidoisocolchicine 2 in 84% yield; the acquisition of 2 constitutes a formal total synthesis of the alkaloid colchicine 1.