Synthesis of pyrazinone ring-containing opioid mimetics and examination oftheir opioid receptor-binding activity

Cyclization of dipeptidyl chloromethyl ketones gave 6-(4-aminobutyl)3-carbo xyethyl-5-methyl-2(1H)-pyrazinone, 3-(4-aminobutyl)-6-carboxyethyl-5-methyl -2(1H)-pyrazinone, and 3,6-bis(4-aminobutyl)-5-methyl-2(1H)-pyrazinone, whi ch were inserted into the enkephalin sequence to give opioid mimetics, Thus , it was confirmed that a pyrazinone ring can be easily inserted into a pep tide sequence in order to evaluate structural components required for biolo gically active peptides.