Site-selective intramolecular (2#pi# + 2#pi#) photocycloaddition of trans-2-butenyl 1-cyano-2-naphthylmethyl ether depending on the polarity of the solvent

摘要

Irradiation of trans-2-butenyl 1-cyano-2-naphthylmethyl ether 1b afforded two kinds of intramolecular (2#pi# + 2#pi#) photocycloadducts at the 1,2-and 3,4-positions in a stereoselective manner. The product ratio was dependent on the solvent polarity based on the nature of the exciplex.