Silica gel-mediated catalyst-free and solvent-free Michael addition of 1,3-dicarbonyl compounds to highly toxic methyl vinyl ketone without volatilization

Silica gel-mediated Michael addition of 1,3-dicarbonyl compounds to methyl vinyl ketone (MVK) and ethyl vinyl ketone (EVK) was carried out to give the corresponding adducts in quite excellent yields. The reactions could be carried out without any catalysts and solvents. In addition, highly toxic MVK and EVK could be employed without significant volatilization. Silica gel could be recycled five times without the decrease of the yields.