Conjugate Addition of Grignard Reagents to Isopropylidene Alkylidenemalonates

In the presence of cuprous chloride, the conjugate addition of Grignard reagents to isopropylidene alkylidenemalonates took place rapidly under mild conditions and in high yield. Thus, a new method for the synthesis of isopropylidene tertiary alkylmalonates was developed. Since the resulting isopropylidene alkylmalonates could be hydrolyzed and decarboxylated to the corresponding monocarboxylic acids or subjected to decarboxylative alcoholysis to form the monocarboxylic esters, a new general method for the synthesis of carboxylic acids and esters branched at the β position was provided.