Stereoselective routes to substituted beta-amino carbonyl compounds via heterodiene cycloadditions of an auxiliary-based C-2-symmetric ketene acetal

Heterodiene cycloadditions of (S,S)-4,5-bis(o-tolyl)-2-methylene-1,3-dioxol ane 1 with a series of substituted beta-amido-alpha,beta-unsaturated carbon yl compounds are diastereoselective (dr greater than or equal to 4:1), The cycloadducts from N-(2-(1-oxoethyl)-3-oxobut-1-enyl)ethanamide 2a can be pu rified by crystallisation and hydrolysed with acid to generate the correspo nding beta-amidoacetic esters, the sequence providing an auxiliary-based st ereoselective route to such compounds. (C) 2000 Elsevier Science Ltd. All r ights reserved.