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Catalytic transfer hydrogenation has been conducted under microwave irradiation in open vessels using high-boiling solvents such as ethylene glycol (bp 198 °C) as the microwave energy transfer agent. Reduction of double bonds and hydrogenolysis of several functional groups were carried out safely and rapidly (3-5 min) at about 110-130 °C with 10% Pd/C as an efficient catalyst and ammonium formate as the hydrogen donor. Diverse types of β-lactam synthons were prepared by the reduction of ring substituents containing alkene and alkylidene groups or conjugated unsaturated esters. Cleavage of the β-lactam ring by hydrogenolysis of the N-C 4 bond of 4-aryl-2-azetidinones was a facile reaction with 10% Pd/C as the catalyst; but no ring scission occurred when Raney nickel catalyst was employed. Dehalogenation of aromatic compounds was also successful with ammonium formate and Pd/C catalyst. Hydrogenolysis of phenylhydrazone of methyl benzoylformate gave the methyl ester of phenylglycine in excellent yield. The techniques described here for microwave assisted hydrogenation are safe, rapid, and efficient and are suitable for research investigation as well as for undergraduate and high school laboratory exercises.

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