Photochemical Origin of the Immunosuppressive SNF4435C/D and Formation of Orinocin through “Polyene Splicing”

Abstract

A splice from life: A photoinduced rearrangement cascade with alternating photochemical and thermal pericyclic steps leads to a novel pyrone compound with chain-contracted polyketide backbone (orinocin (2)). The excision of three propionate units from the polyene precursor, spectinabilin (1), proceeds via the immunosuppressive SNF4435C/D and yields an unusual triketide, mesitylene (see scheme).