1967or acetone (79-82 kcal).13 Moreover, the reaction was not quenched by l,&pentadiene (59 kcal; 0.1 M). These results indicate that the photoreaction occurs from the singlet state. This is quite unusual because, to our best knowledge, hydrogen abstraction of olefins from the singlet states has not been reported. The quantum yield of the reaction of IC was 0.049 (consumption of IC) and was much higher than that of 1,bhydrogen transfer reaction of an a-alkylstyrene from the triplet state (@ = 0.0005).4 The isotope effects were measured by using lc-d2.14 The value, @H/@D = 2.0, is considerably smaller than that of the triplet-state reaction of the alkylstyrene (@H/@D N 5): In view of these results, it is conceivable that the photocyclization of IC involves sequential electron-proton transfer15 rather than one-step hydrogen atom transfer, although electron transfer from amides to excited olefins has not been reported. The scope and further mechanistic studies of the photocyclization are being studied. Registry No. la, 76916-92-2; lb, 76916-93-3; IC, 76916-94-4; Id, 76916-99-9; N,N-diethyl-2,2-dimethyl-3-oxo-3-phenylpropion~ide, 76917-00-5; N,N-diisopropyl-2,2-dimethyl-3-oxo-3-phenylpropionamide, 76917-01-6; N,N-dibenzyl-2,2-dimethyl-3-0~0-3-phenylpropionamide, 61845-93-0; N,N-diallyl-2,2-dimethyl-3-oxo-3phenylpropionamide, 76917-02-7; methyl iodide, 74-88-4. 76916-95-5; 2c, 76916-96-6; 2~', 76916-97-7; 2d, 76916-98-8; 2d', (13) Murov, S. L. "Handbook of Photochemistry"; Marcel Decker: New York, 1973. (14) A similar measurement of isotope effects has been reported Padwa, A.; Eisenhardt, W.; Gruber, R.; Pashayan, D. J. Am. Chem. SOC. 1971,93, 6998. (15) (a) Padwa, A.; Gruber, R.Summary: Tris(tetra-n-butylammonium) hydrogen pyrophosphate was used to prepare dimethylallyl pyrophosphate (1-OPP), 7-methylocta-2,6-dien-l-y1 pyrophosphate (2-0PP), geranyl pyrophosphate (3-0PP), 2fluorogeranyl pyrophosphate (4-OPP), and farnesyl pyrophosphate (5-OPP) from the corresponding alcohols in moderate yields by a two-step sequence via the corresponding primary, allylic bromides.
