Photo-induced reduction of fluoren-9-ol and its acetate by aliphatic amines

Abstract

Irradiation of fluoren-9-ol and its acetate in the presence of an aliphatic amine gave fluorene as the major product. The yield of fluorene depended upon the character of amine and increased in the order of primary < secondary < tertiary amines. By the use of deuteriated reagents ([²H₁]methanol and [²H₃]acetonitrile) it was revealed that the major process was electron transfer followed by proton transfer. A radical reaction also participated as a minor process. A possible reaction mechanism similar to the photo-induced Birch reduction was proposed.