Journal of Photosciences

Photoreaction of N-(2-Halophenyl)cyclohexanecarboxamide: Synthesis of 2-Alkylbenzoxazole

Volume 7(2000), 135-138 page

저자: Yong-Tae Park, Moon-Sub Kim, Young-Woo Kwak, Jae-Keun Lee, and Soo-Dong Yoh, Woo-Sik Kim

   7-4-135.pdf (46.1K)

Keywords: 2-cyclohexylbenzoxazole  N-(2-halophenyl)cyclohexanecarbox amide  intramolecular photosubstitution  photoreduction  photo-Fries type

The photochemical behavior of haloarene tethered to alkyl by an amide bone (1, 2) was studied.
The photoreaction of N-(2-bromophenyl) cyclohexanecarboxamide (1b) in basic medium afforded intramolecular substituted product, 2-cyclohexylbenzoxazole (4) and reduced product, N-phenylcyclohexanecarboxamide (5) in 33 and 26 % yields, respectively.
The chloro analogue (1a) produced photo-Fries type and photosubstituted products (6, 4), whereas the iodo analogue produced extensively photoreduced product 5.
N-(2-bromophenyl)-N-methylcyclohexanecarboxamide (2), which can not exist as imidol form, produced a photocyclized product, supporting an imidol form is involved in the intramolecular photosubstitution.
Since the photoreduction but the photosubstitution reaction is retarded by the presence of oxygen, a triplet state for the photoreduction and a singlet state for the photosubstitution are involved.