Phosphate Derivatives of Natural Lactones. I. Synthesis of Novel Isoalantolactone Dialkylphosphonates

Novel isoalantolactone dialkylphosphonates were synthesized in 70-87% yields by reacting this eudesmanolide with dialkylphosphites. Their structures were proved by spectral analysis using IR, PMR, 13C and 31P NMR, and two-dimensional 1H-1H (COSY) spectroscopy. The reaction of isoalantolactone with dialkylphosphites is highly stereoselective.