Total Synthesis and Stereochemical Proposal of the Hexaene Framework of Bacillaene.

The central hexaene core of the labile polyene antibiotic bacillaene bearing three -configured olefins was prepared with excellent geometrical purity by an iterative cross-coupling strategy, involving improved syntheses of bimetallic reagents and efficient protocols for stereoselective polyene generation, revealing insights into the origin of bacillaene's instability. Furthermore, a useful method for monitoring polyene iteration by UV-vis shift analyses and the absolute stereochemistry of this core by biosynthetic gene cluster analysis are reported.