Diketone 3, available by cyclization of keto acid 2 with PPA/HOAc, undergoes intramolecular oxidative cyclization to 4 by exposure of its dienolate to FeCl₃ in DMF at −78 °C. Convenient monomethylenation of 4 with optical resolution to give optically pure (+) - and (−) - 12 is described.