Abstract Alkylation of umbelliferone and nitrophenol with chloroacetone, 3-chlorobutanone, 2-chlorocyclopentanone and 2-chlorocyclohexanone gave the corresponding 2- coumaryloxy and 2-nitrophenoxy ketones. The 2-coumaryloxy ketones were used as fluorogenic substrates to detect Baeyer–Villiger monooxygenases activities of microbial cultures in high-throughput using microtiter plates. The 2-coumaryloxy ketones were ...