Enantioselective Synthesis of the Macrocyclic Pyrrolizidine Alkaloid Yamataimine

Abstract

Abstract Described is a short-step synthesis of optically active yamataimine, a 12-membered pyrrolizidine alkaloid of retronecine type. Methyl (1S,5R)-5-methyl-2-oxocyclopentanecarboxylate derived from (R)-(+)-pulegone was converted into the necic acid component required for the synthesis of yamataimine, in a nine-step sequence. Regioselective coupling of (+)-retronecine with the necic acid component via tin-mediated regioselective acylation followed by macrolactonization led to the first synthesis of (+)-yamataimine.