AsymmetricvinylogousMannichreaction (VMR) of 2-(tert-butyldimethylsilyloxy)furan (TBSOF, 1) with (RS)- or (SS)-t-BS-imines (3) furnished 5-aminoalkylbutenolides 7a–k in 75–87% yields with anti/syn ratios ranging from 75:25 to 97:3. Butenolides 7a–f,k were readily converted into substituted lactones 8 and 5 and 6-substituted 5-hydroxypiperidin-2-ones 11a–g, which are, in turn, key intermediates for
the chemoselective cleavage of benzylideneacetals having sensitive functional groups under mild conditions. It is easy to perform on large scale owing to minimal catalyst loading (0.5 mol-%). Several sensitive functional groups such as TBDPS ether, -OMs, -OAc, allyl ether, N-Boc, N-Fmoc and N-Cbz are stable under the reaction conditions. In addition, benzylideneacetal is selectively cleaved in the