Enantio- and Diastereoselective Cu(II)-Catalyzed Conjugate Borylation/Michael Addition Cascade: Synthesis of Spiroindane Boronates.

We report a Cu(II)-(,)-Pr-FOXAP-catalyzed borylative Michael/Michael addition cascade cyclization of unsymmetrical dienone for the synthesis of highly substituted and functionalized all-carbon spiroindane boronates under mild conditions. A series of optically active spiroindanes bearing boronic ester were obtained with excellent yields and good to excellent enantioselectivities (≤97% ee) and diastereoselectivities (up to >20:1 dr). In addition, scale-up synthesis of this method and synthetic transformations of spiroindane boronates are also illustrated.