Biosynthesis of bisorbicillinoid in Trichoderma sp USF-2690;: Evidence for the biosynthetic pathway, via sorbicillinol, of sorbicillin, bisorbicillinol, bisorbibutenolide, and bisorbicillinolide

An incorporation study of [1-C-13] and [1,2-C-13(2)] labeled sodium acetates into sorbicillinol 1 established a ring closure system between C-1 and C-6 and the positions that were oxidized and/or methylated on a hexaketide chain. Subsequent investigations, using C-13-labeled 1 prepared from [1-C-13] labeled sodium acetate, clearly demonstrated that both bisorbicillinol 2 and sorbicillin 6 incorporated C-13-labeled 1 into their carbon skeletons. C-13-labeled bisorbicillinols 2 derived from [1-C-13]- and [2-C-13]-labeled sodium acetates clearly indicate that these were on the biosynthetic route from 1 to bisorbibutenolide (bislongiquinolide) 3 and bisorbicillinolide 4 via 2 as a branching point in the fungus.