A Miyashita, Y Suzuki, Nagasaki, I, C Ishiguro, K Iwamoto, T Higashino
CHEMICAL & PHARMACEUTICAL BULLETIN 45(8) 1254-1258 1997年8月 査読有り
Refluxing of a mixture of benzaldehyde (la), 1,3-dimethylbenzimidazolium iodide (7), p-nitroaniline (9b) as an oxidizing agent, and 1,8-diazabicyclo[5,4,0]-7-undecene (DBU) in MeOH afforded methyl benzoate (2a) in good yield, Other methyl arenecarboxylates 2 were similarly obtained from arenecarbaldehydes 1, We showed that this aroylation proceeds via the 2-aroyl-1,3-dimcthylbenzimidazolium salt (8), The 1,2,4-triazolium salt (18) and the naphtho[1,2-d]imidazolium salt (19) were also effective catalysts for this oxidative aroylation, However, the aroylation did not proceed with the imidazolium salt (20), Tn the presence of flavins (25a-c), arenecarbaldehydes 1 reacted in MeOH under aerobic conditions catalyzed by the benzimidazolium salt 7 to give the corresponding methyl arenecarboxylates 2, 1-Methyl-3-[3-(10-phenylisoalloxazin-3-yl)propyl]benzimidazolium bromide (27) is an effective complex catalyst for this oxidative aroylation.