Reversed diastereoselectivity in the Yang photocyclization upon introducing a cyclopropyl group at the alpha position to carbonyls

1-Benzoy1-1-(o-ethylphenyl)cyclopropane favors the E-indanol formation in its photochemical reaction and the selectivity is maximized in methanol. These are exactly opposite to the photochemical behavior of α-(ortho-ethylphenyl)-acetophenone. Our computational studies suggest that the different stereochemical outcome of the two systems originates from the geometric difference of initially formed biradical intermediates.