Synthesis and cytotoxic activity of some novel polycyclic γ-butyrolactones

Baeyer–Villiger oxidation of 5-aryl-7,11,11-trimethyltricyclo[5.4.0.03,6]-undec-1-en-4-ones 4a–h by H2O2 and formic acid in methanol yields mixtures of 3b,7,7-trimethyl-3-phenyl-3,3a,3b,4,5,6,7,8a-octahydro-1H-indeno-[1,2-c]furan-1-ones 8a–h and 3b,7,7-trimethyl-3-phenyl-3,3a,3b,4,5,6,7,8a-octahydro-1H-indeno-[1,2-c]furan-2-ones 9a–h in high yields. The obtained butyrolactones 8a–h display cytotoxic activity against a number of human cancer cells.