Arylpropionylpiperazines as antagonists of the human melanocortin-4 receptor

A series of 3-arylpropionylpiperazines were synthesized as antagonists of the melanocortin-4 receptor. Their potency was found to be increased by replacing the α-methyl substituent of the initial lead 11 with a larger s-Bu or i-Bu group. Further potency enhancement was observed when a glycine or β-alanine was incorporated onto the benzylamine. Some compounds demonstrated good potency, moderate selectivity, and oral bioavailability.

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