Catalyzes the flavin-dependent Baeyer-Villiger oxidation of 1-deoxy-11-oxopentalenic acid to pentalenolactone D in the biosynthesis of pentalenolactone antibiotic. 1-deoxy-11-oxopentalenate + H(+) + NADPH + O2 = H2O + NADP(+) + pentalenolactone D Binds 1 FAD per subunit. Antibiotic biosynthesis; pentalenolactone biosynthesis. Belongs to the FAD-binding monooxygenase family.