Changing course with an additive: A striking example of the effect of TMSCl on lithium amide reactivity

Article abstract of DOI:10.1016/0040-4039(96)00817-9

When a solution of diethyl maleate and acetophenone is added to a cooled (-78°C) solution of a lithium amide the maleate derivative 3 is given in good yield. Pre-treatment of the lithium amide with TMSCl alters the course of this reaction dramatically. With half an equivalent of this additive the Michael adduct 4 is given in 62% yield while employing three equivalents leads to the silyl enol ether 5 in >85% yield.