Photoaddition Reaction of N-Acetyldiphenylmethyleneamine with Cyclic and Acyclic Olefins. An Example of Heavy Atom Effect in Photoreaction

Abstract

Irradiation of N-(diphenylmethylene)acetamide (N-acetyldiphenylmethyleneamine, 1) in cyclopentene gave N-[1,1-diphenyl-1-(cyclopenta-2′-enyl)niethyl]acetaniide, the addition product of cyclopentene to the C=N bond of imine 1, in 31% yield. The photoreaction of 1 was observed in other cyclic and acyclic olefins. The reactivity of the olefins decreases in the order; cyclopentene>cyclohexene>cyclooctene>2-pentene\simeq2-hexene. The photoreaction is promoted by the presence of the heavy atom solvent or the sensitizer. The mechanism of photoreaction is discussed in terms of the excited triplet state of the imine.

The effect of heavy-atom solvents on the photooxidation of anthracene

“…For example, Cowan and Drisko ( 1-3) have detected an increase in the yield of trans-photodimer due to a heavy-atom effect in photodimerization of acenaphthylene. W e have found that heavy-atom solvents are effective for accelerating the photoaddition (4) and photoreduction ( 5 ) of N-acetyldiphenylketimine in spite of the molecule having a carbonyl group.…”