First Synthesis of (+-)-10#beta#-hydroxy-13#beta#-methylcyclohexa[a]quinolizidine. A Convenient Route to the ABC-part of 8-Azasteroids

摘要

The first synthesis of racemic 10#beta#-hydroxy-13#beta#-methylcyclohexa[a]quinolizidine is reported. Original construction of AC-bicyclic system is achieved by lateral metallation of 2-ethylpyridine followed by a Robinson annelation, with the creation of a quaternary picolinic carbon center. Functionalization of the A-ring and construction of the B-ring by a stereocontrolled reduction of the pyridinium salt and final hydrogenations afford the ABC-part of an 8-azasteroid.