Sodium Telluride-Mediated Carbon-Carbon Bond-forming Reactions

Abstract

Sodium telluride, prepared by heating tellurium and sodium hydride in a 1: 2 molar ratio in dry N, N-dimethylformamide, readily debrominates a bromoacetic ester [2] at low temperatures to generate an ester enolate anion [13], which undergoes a Reformatskytype reaction with various nonenolizable aldehydes [1] to give the corresponding α, β-unsaturated esters [3] in good to moderate yields. Haloacetonitrile [4] reacts similarly to afford α, β-unsaturated nitriles [5] in moderate yields. Although the results were unsatisfactory with N, N-dialkylbromoacetamides [7], N, N-dialkyltrichloroacetamide was found to produce N, N-dialkyl- p p-aryl- α-oxopropionamides [10] as a major product. On a similar treatment, 4-cyanobenzyl bromide [11] condenses with piperonal in a reductive way to give 4'-cyano-3, 4-methylenedioxystilbene [12] among other products.