Catalyzes a Baeyer-Villiger oxidation reaction, i.e. the insertion of an oxygen atom into a carbon-carbon bond adjacent to a carbonyl, which converts ketones to esters or lactones using NADPH as an electron donor. Converts cyclopentanone to 5-valerolactone, a step in the degradation pathway of cyclopentanol. Besides cycloalkanones, can also act on methylated and other alkylated cycloalkanones, and on methylated cycloalkenones, with high enantioselectivity in some cases. Cannot use NADH instead of NADPH. cyclopentanone + H(+) + NADPH + O2 = 5-valerolactone + H2O + NADP(+) Alcohol metabolism; cyclopentanol degradation; 5-valerolactone from cyclopentanol: step 2/2. Homotetramer. Cells lacking this gene are not capable of growth on cyclopentanol or cyclopentanone as a sole carbon and energy source. Belongs to the FAD-binding monooxygenase family.