Microwave-Assisted Rapid and Simplified Hydrogenation^1,

Abstract

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.

Synthesis, characterization and spectral studies of various newer long chain aliphatic acid (2-hydroxy benzylidene and 1H-indol-3-ylmethylene) hydrazides as mosquito para-pheromones

“…6 From the synthetic point of view, hydrazones are important synthones for several transformations and their synthesis from various precursors is well documented. 7 Various long chain acids and esters are reported as semiochemicals of egg origin that affect the ovipositional behavior of the mosquito Aedes aegypti, 8 which is a vector of dengue, chikungunya and yellow fever. Similarly, substantial documentation is available for oviposition-stimulating semiochemicals such as nheneicosane, 9 trimethylphenol, 4-methylphenol, 10 3-methylindole.…”

One-Pot Reactions: Expeditious Synthesis of Diverse Organic Compounds of Current Interests

“…This reaction produced hydroxy-substituted amides. It was not possible to differentiate the rate of hydrogenolysis of the benzyl ether and N-C4 bond cleavage [5]. It appeared both of these reactions take place simultaneously.…”

“…β-Lactams that have an aromatic group at the C-4 position of the ring were hydrogenated and cleaved to open chain amides by catalytic transfer hydrogenation method [5]. Ammonium formate in the presence of 10% Pd/C was found to be the best reagent for this purpose.…”

Molecular Iodine-Catalyzed Reactions: Our Own Account

“…The reactions described above were conducted under microwave irradiation method [13]. It was crucial to observe that all these reactions were successfully performed in domestic or automated microwave oven.…”