Hypervalent Iodine-Mediated Diastereoselective α-Acetoxylation of Cyclic Ketones

A binary hybrid system comprising a hypervalent iodine(III) reagent and BF(3)•OEt(2) Lewis acid was found to be effective for the diastereoselective α-acetoxylation of cyclic ketones. In this hybrid system, BF(3)•OEt(2) Lewis acid allowed the activation of the hypervalent iodine(III) reagent and cyclic ketones for smooth α-acetoxylation reaction, achieving high diastereoselectivity. This hypervalent iodine-mediated α-acetoxylation of the cyclic ketone reaction plausibly undergoes an S(N)2 substitution mechanism via an α-C-bound hypervalent iodine intermediate. The diastereoselectivity of the reaction mainly originates from thermodynamic control.