Quinolizidines. XII. Synthetic Incorporation of Ethyl Cincholoiponate into a Tricyclic Intermediate Adaptable to Chiral Syntheses of the 10-Hydroxy-9-methoxybenzo [a] quinolizidine-Type Alangium Alkaloids

Abstract

For the purpose of securing a key intermediate for chiral syntheses of the 10-hydroxy-9-methoxybenzo [a] quinolizidine-type Alangium alkaloids (type 4), the tricyclic ester (-)-15 has been synthesized from ethyl cincholoiponate [(+)-6] and 4-benzyloxy-3-methoxyphenacyl bromide by the "cincholoipon-incorporating method"through the intermediates (+)-7, 10, 8, (-)-11, (-)-12, (+)-13, (+)-14, (+)-17, and 16.