Mitsunobu C-Alkylation of Meldrum's Acids

C -Dialkylation of Meldrum's acid ( 2a ) and 5-benzyl Meldrum's acid ( 2b ) can be achieved through Mitsunobu dehydration using allylic and arylmethyl alcohols as alkylating agents. This is the first time that the Mitsunobu reaction is successfully applied to the C -alkylation of a highly enolizable cyclic β-dicarbonyl system. With primary (allylic and arylmethyl) alcohols, the alkylations always take place at the carbon bearing the hydroxy group. For secondary allylic alcohols, a catalytic amount of Pd(0) must be added to enhance the regioselectivity of C -alkylation over O -alkylation. With (Ph 3 P) 4 Pd(0) as a catalyst, the reaction occurs specifically at the less hindered carbon, and the configuration of the resultant double bond is always trans . Attempts to monoalkylate Meldrum's acids 2a and 2b failed.