A Phosphine-Catalyzed [3+2] Cycloaddition Strategy Leading to the First Total Synthesis of (−)-Hinesol

In one step, the skeleton of cis-spirovetivanes was constructed with high stereoselectivity by the phosphine-catalyzed [3+2] cycloaddition reaction of tert-butyl 2,3-butadienoate or 2-butynoate with 3-methyl-2-methylenecyclohexanone (5). This method was exemplified by the first highly efficient total synthesis of natural product (−)-hinesol, which is an active ingredient of cerebral circulation and metabolism improvers.