Synthesis of Taxane ABC Tricyclic Skeleton from Lycoctonine

Abstract

A new conversional synthesis of the ABC ring system of taxoids from the C 19-diterpenoid alkaloid lycoctonine was developed in 6 steps with 2% overall yield. The distinctive features of the conversion include pinacol rearrangement, enlargement of ring B, and opening of a four-membered ring.

Epoxide Opening of a 7,17-Seco–7,8-Epoxy-C19-Diterpenoid Alkaloid

“…We started to develop conversional synthesis of taxoids starting from C 19 -diterpenoid alkaloids since early 1990s. During the course, several novel approaches to the taxane ABC ring system and numerous intriguing reactions of C 19 -diterpenoid alkaloids have been reported [5][6][7][8][9][10][11][12][13]. We have found that modifications of ring B, including cleavage of C7-C17, enlargement of ring B, functionalization of C-7 and C-8 for assembly of the Δ 8,15 bridgehead double bond, and introduction of functional groups with specific configurations, were part of the critical steps to our successful conversions from aconitine-type C 19 -diterpenoid alkaloids [5][6][7] to the core structure of taxoids.…”