Temperature-Dependent Direct Enantioconvergent Silylation of a Racemic Cyclic Allylic Phosphate by Copper(I)-Catalyzed Allylic Substitution

The near-quantitative transformation of a racemic cyclic allylic phosphate to a highly enantiomerically enriched allylic silane by allylic substitution with a silicon nucleophile is reported. The reaction is catalyzed by a chiral NHC-copper(I) complex. Experimental analysis revealed a rare case of a direct enantioconvergent transformation where the enantiomeric allylic phosphates converge to the same allylic silane by two distinctive S(N)2 pathways with opposite diastereofacial selectivity.