Synthesis and structure–activity relationships of a new class of 1-oxacephem-based human chymase inhibitors

1-Oxacephem derivatives were synthesized and evaluated as a novel series of chymase inhibitors. Structure–activity relationship studies of 1-oxacephems led to compound 34, which exhibited 6 nM inhibition of human chymase and high selectivity for human chymase compared to other serine enzymes.