Asymmetric Total Syntheses of Macroline-Type Alkaloids Alstomicine and Alstofolinine A

Abstract

Macroline-type monoterpenoid indole alkaloids represent a fascinating class of natural products with polycyclic structures, diverse biological and pharmacological activities. Herein we report the asymmetric total syntheses of two this type alkaloids, (–)-Alstomicine and (–)-Alstofolinine A. Notably, these two alkaloids are divergently synthesized from a common indole-fused azabicyclo[3.3.1]nonane intermediate, which was easily obtained via a Mannich-type cyclization. A SmI2 mediated Reformatsky reaction and a Pd-catalyzed carbonylative lactonization are employed to construct the lactone moieties presented in Alstomicine and Alstofolinine A respectively.