Efficient syntheses of oncinotine and neooncinotine.

ABSTRACT

We have synthesized two natural alkaloids, oncinotine (1) and neooncinotine (2), by means of efficient ring-closing metathesis (RCM) reactions. The required dienes for RCM were assembled from three basic components 2-allylpiperidine (5), 9-decenoic acid (6), and diamines 7. We developed two different methods to achieve the linkage the Michael addition of acrylamide and two amidations of succinic anhydride. The Grubbs catalyst was used to form the 17- and 18-membered lactams in 50% and 68% yields, respectively.