Diastereoselectivity in (2(pi) + 2(pi)) Photocycloaddition of Cholesteryl Cinnamate to Methyl 9-Phenanthrenecarboxylate: Control of the Stereoselectivity in Liquid Crystalline Phase

Photocycloaddition of cholesteryl cinnamate with methyl 9-phenanthrenecarboxylate in benzene at ambient temperature gave a (2(pi) + 2(pi)) photocycloadduct in 8% diastereomeric excess (de). When the reaction was carried out in neat conditions at 150–170 °C, the major product was reversed to another diastereomer, in which de was given in 14%.