Fischer indolization and its related compounds. XVI. Vilsmeier-Haack reaction of N-methyl-1,2,3,4-tetrahydrocarbazole derivatives.
作者:YASUOKI MURAKAMI、HISASHI ISHII
DOI:10.1248/cpb.29.711
日期:——
Vilsmeier-Haack reaction of 6-chloro-1, 2, 3, 4-tetrahydro-9-methylcarbazole (1b) with 3 mol eq. POCl3 at 70°gave three compounds, 6-chloro-1, 2, 3, 4-tetrahydro-9-methyl-carbazole-1, 1-dicarboxaldehyde (4), 6-chloro-3, 4-dihydro-9-methylcarbazole-1 (2H)-one (5b), and 6-chloro-1, 2, 3, 4-tetrahydro-1-hydroxy-9-methylcarbazole-1-carboxaldehyde (6), while no 4a-formylated product1) was obtained. On the other hand, the reaction of the same compound (1b) with 1.3 mol eq. POCl3 at 100°gave 6-chloro-1, 2, 3, 4-tetrahydro-9-methyl-carbazole-1-carboxaldehyde (20), 5b, 6-chloro-1, 2, 3, 4-tetrahydro-9-methylcarbazole-7-carboxaldehyde (3b), and an aromatized compound, 6-chloro-1, 9-dimethylcarbazole-3-carboxaldehyde (2b). The formation mechanism of the aromatized compound (2b) is considered to involve elimination of a dimethylamino group and formation of 6-chloro-1, 9-dimethylcarbazole (21) as an intermediate.
6-chloro-1, 2, 3, 4-tetrahydro-9-methylcarbazole (1b) 与 3 mol eq.在 70° 下与 3 mol eq 的 POCl3 反应,得到三种化合物:6-氯-1,2,3,4-四氢-9-甲基咔唑-1,1-二甲醛 (4)、6-氯-3,4-二氢-9-甲基咔唑-1 (2H)-one (5b)、和 6-氯-1,2,3,4-四氢-1-羟基-9-甲基咔唑-1-甲醛 (6),而没有得到 4a 甲酰化产物1)。另一方面,相同化合物 (1b) 与 1.3 mol eq.POCl3,在 100°条件下反应,得到 6-氯-1,2,3,4-四氢-9-甲基咔唑-1-甲醛(20)、5b、6-氯-1,2,3,4-四氢-9-甲基咔唑-7-甲醛(3b)和芳香化化合物 6-氯-1,9-二甲基咔唑-3-甲醛(2b)。芳香化化合物(2b)的形成机理被认为是消除二甲基氨基并形成 6-氯-1,9-二甲基咔唑(21)作为中间体。