Catalytic diastereoselective synthesis of diquinanes from acyclic precursors.

Upon exposure of up to 10 mol % tributylphosphine, electron-deficient 1,7-enynes undergo [3 + 2] cycloaddition to afford bicyclo[3:3:0] ring systems. In all but one case, products were obtained in >95:5 de, as determined by 1H NMR. This methodology enables concise and diastereoselective access to diquinane ring systems, whereby three contiguous stereogenic centers are set in a single manipulation.