Photocyclization of alpha-(o-ethylphenyl)acetophenone in zeolites

The diastereoselectivity in the photocyclization of alpha-(o-ethylphenyl)ac etophenone (1) to 1-methyl-2-phenyl-2-indanol was studied in zeolites X and Y, and compared with that in isotropic solvents. The yields of E-diastereo mer at the irradiation of 1 in protic solvents were higher than those in ap rotic solvents. The ratios of E-diastereomer to Z-diastereomer in zeolites X and Y were much higher than those in isotropic solvents. The E/Z ratios a t the irradiation of 1 in zeolites X were also found to be dependent on the cations present. As the cation size increased from Li+ to Cs+, the ratio d ecreased. However, any pattern in the E/Z ratios was not found in zeolites Y. The diastereoselectivity observed in the zeolites was interpreted by the conformational restriction imposed by the cavity size. An efficient oxidat ion of 1 in zeolites RbX and CsX was also observed.