Photocycloaddition Reaction of Aryl-1,3-butadiynes with Some Olefins

Article abstract of DOI:10.1021/jo00302a016

1-Aryl-1,3-butadiynes 1-6 were photolyzed in 2,3-dimethyl-2-butene (DMB) to obtain <2+2> type photocycloadducts 7-12, except for 5 which yields two primary photoadducts (11, 13) and a secondary photoadduct (14).Azulene quenching, fluorescence, and exciplex emission studies suggest the reaction to proceed from both singlet and triplet excited states in compounds 1-4 while only the triplet excited state is reactive in compounds 5 and 6.