Catalytic Action of Azolium Salts. VIII. Oxidative Aroylation with Arenecarbaldehydes Catalyzed by 1,3-Dimethylbenzimidazolium Iodide.
作者:Akira MIYASHITA、Yumiko SUZUKI、Izuru NAGASAKI、Chie ISHIGURO、Ken-ichi IWAMOTO、Takeo HIGASHINO
DOI:10.1248/cpb.45.1254
日期:——
Refluxing of a mixture of benzaldehyde (1a), 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-dimethylbenzimidazolium 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). In 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.
将苯甲醛(1a)、1,3-二甲基苯并咪唑鎓碘化物(7)和作为氧化剂的4-硝基苯胺(9b)与1,8-二氮杂双环[5,4,0]十一碳-7-烯(DBU)的甲醇溶液回流反应,可得到产率良好的苯甲酸甲酯(2a)。其他甲基芳香羧酸酯2也可通过类似的途径从芳香醛1得到。我们证明,这种羰基化反应是通过2-羰基-1,3-二甲基苯并咪唑鎓盐(8)进行的。1,2,4-三唑鎓盐(18)和萘并[1,2-d]咪唑鎓盐(19)也是这种氧化羰基化反应的有效催化剂。然而,咪唑鎓盐(20)并不能促使该反应进行。在黄素(25a-c)存在下,芳香醛1在甲醇中经苯并咪唑鎓盐7催化的有氧条件下反应,生成相应的甲基芳香羧酸酯2。1-甲基-3-[3-(10-苯基异黄酮-3-基)丙基]苯并咪唑鎓溴化物(27)是一种有效的氧化羰基化反应复合催化剂。