A general and efficient strategy for 7-aryloctahydroindole and cis-3a-aryloctahydroindole alkaloids: Total syntheses of (±)-γ- lycorane and (±)-crinane

A general and efficient approach to both 7-aryloctahydroindole and cis-3a-aryloctahydroindole alkaloids has been developed. The key step involves Michael additions of the corresponding kinetics and thermodynamics lithium enolates of ketone 9 to the versatile building blocks: nitroethylene 10. Two representative members, (±)-γ-lycorane and (±)-crinane, have been synthesized in 22 and 36% overall yields, respectively.