Biosynthesis of phomactins: common intermediate phomactatriene and taxadiene

The stereochemical course of GGDP cyclization in the biosynthesis of phomactins is proposed by the stereochemistry of a cyclization product, phomacta-1(14),3,7-triene, isolated from Phomasp. and the results of incorporation experiments with [1-13C]- and [1,2-13C2]acetates.