Comparative conventional and microwave assisted synthesis of heterocyclic oxadiazole analogues having enzymatic inhibition potential

A comparative microwave assisted and conventional synthetic strategies were applied to synthesize heterocyclic 1,3,4-oxadiazole analogues as active anti-enzymatic agents. Green synthesis of compound1was achieved by stirring 4-methoxybenzenesulfonyl chloride (a) and ethyl piperidine-4-carboxylate (b). Compound1was converted into respective hydrazide (2) by hydrazine and then into 1,3,4-oxadiazole (3) by CS(2)on reflux. The electrophiles,N-alkyl/aralkyl/aryl-2-bromopropanamides (6a-p) were synthesized and converted toN-alkyl/aralkyl/aryl-2-propanamide derivatives (7a-p) by reaction with3under green chemistry. Microwave assisted method was found to be effective relative to conventional method.C-13-NMR,H-1-NMR and IR techniques were availed to corroborate structures of synthesized compounds and then subjected to screening against lipoxygenase (LOX), alpha-glucosidase, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. A number of compounds presented better potential against these enzymes. The most active compounds against LOX and alpha-glucosidase enzymes were subjected to molecular docking study to explore their interactions with the active sites of the enzymes.