Stereocontrolled Synthesis of Pseurotin A2.

We report synthesis of two diastereomeric structures previously proposed for the complex secondary metabolite pseurotin A2. Both structures were accessed from the same building blocks taking advantage of a stereodivergent nickel(II)-diamine-catalyzed 1,4-addition of a chiral 2-alkoxycarbonyl-3(2H)-furanone. Late-stage Csp-Csp3 cross-coupling of a highly functionalized bromoalkyne featured in the pseurotin A2 side-chain assembly. The work supports the 2016 stereochemical revision of pseurotin A2 and represents the first chemical synthesis of this natural product.