Reaction of diethyl mesoxalate with active methylene compounds : an interesting outcome

Diethyl mesoxalate reacts separately with each of Meldrum's acid, indan-1,3-dione and diethyl malonate - all active methylene compounds - on neutral alumina either at room temperature or under microwave irradiation to furnish expeditiously the corresponding tertiary carbinols in very good yields. However, when the reaction of diethyl mesoxalate with a number of other active methylene compounds was tried similarly or by heating at 60-70 degrees C, the reactions either led to single products, which were too unstable to be isolated, or simply failed. Our findings, shedding new light on the reactivity of diethyl mesoxalate, are presented below.