Michael monoadditions of nitromethane or nitroethane with electrophilic gem-disubstituted alkenes over alumina under microwave irradiation

Nitromethane or nitroethane react with electrophilic alkenes RCHC(CN)(Y) with Y=CO2R′, CN, CONH2 adsorbed on alumina to give selectively at room temperature or under focused microwave irradiation new Michael monoadducts (two diastereoisomers) or (four diastereoisomers) after a few minutes. It is possible to obtain only two diastereoisomers of by reaction of the corresponding nitroalkene and methylcyanoacetate in the presence of catalytic amounts of piperidine. Mechanisms are proposed. Some examples of addition of nitroalkanes with electron-deficient alkynes in dry media coupled with microwave irradiation conditions are also described.