Results Photoisomerization. Irradiation of anti-(CH3, CH3) B (3; 2 with R1= R2= CH3) in degassed CH3CN produces an isomeric lactone (eq 1). The reaction can be followed (1)(a) Tel-Aviv University.(b) Stab University of New York at Stony Brook.(2)(a) Koeower, EM; Pazhenchevsky, B.; Hershkowitz, EJ Am. Chem. SOC. 1978, 100, 6616-6618.(b) Koeower, EM; Bemtein, J.; Goldberg, I.; Pazhenchevsky, B.; Goldstein, E. Zbid. 1979, 101, 1620- ...