Anion Reactions of 1,3-Dithiane 1,3-Dioxide with Carbonyl Compounds: High Diastereoselectivity with Aromatic Aldehydes under Conditions of Equilibrium Control
作者:Varinder K. Aggarwal、Richard Franklin、John Maddock、Graham R. Evans、Abraham Thomas、Mary F. Mahon、Kieran C. Molloy、Martin J. Rice
DOI:10.1021/jo00112a042
日期:1995.4
We have investigated the anion chemistry of trans-1,3-dithiane 1,3-dioxide (4) with aldehydes and ketones, and we have found that this reagent undergoes highly selective addition reactions with aromatic aldehydes but only when reactions are under equilibrium control (achieved using Na anion of 4). Other metals invetsigated (Li, Mg, Al, Ce, Ti) gave either poorer selectivity or caused decomposition of 4. Zn-4 did give improved selectivity at low temperature but only with aromatic aldehydes. Reactions with ketones were limited to those without a-branching. A model that accounts for the high diastereoselectivity observed with aromatic aldehydes is presented.