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