BF3•OEt2-Promoted Diastereoselective Diacetoxylation of Alkenes by PhI(OAc)2

Selective syn and anti diacetoxylations of alkenes have been achieved using a PhI(OAc)(2)/BF3 center dot OEt2 system in the presence and absence of water, respectively. A broad range of substrates including electron-deficient alkenes (such as alpha,beta-unsaturated esters) could be elaborated efficiently at room temperature with this methodology, furnishing the desired products in good to excellent yields and diastereoselectivity. In particular, a multigram-scale diastereoselective diacetoxylation of methyl cinnamate (5.00 g) was also accomplished in a few hours, maintaining the same efficiency as small-scale reaction. This novel methodology provides an alternative approach for the preparation of various 1,2-diols.