Formal synthesis of ent-Cephalotaxine using a one-pot Parham-aldol sequence

Abstract

A short formal synthesis of ent-Cephalotaxine is achieved. The approach features a new Lewis acid mediated [2,3]-Stevens rearrangement of N-allylated prolineamide to generate a key quaternary stereogenic center. Additionally, a one-pot Parham–aldol sequence was developed to rapidly assembly two of the four rings in the cephalotaxine core.