4220 J . Org. Chem., Vol. 43, No. 21,1978
Schmitz, McDonald, and Vanderah
matography of the crude mixture on silica gel gave 54 mg of 6 and 73 mg (42%)of 15. A second chromatography (ether 5% in benzene) gave 49 mg (28%) of pure 15. Quantum Yield Determinations. Solutions of different ketones 1-6 M) in spectrograde acetonitrile or in a 1 M solution of acetone in acetonitrile were subjected to three freeze-pump-thaw cycles and sealed a t mm in 10-mm 0.d. quartz cells. Irradiations were carried out using a 313-nm line produced by a Bausch and Lomb monochromator. Light intensities were measured by ferrioxalate actinometry. Photolyses were run to
