均相体系中铱催化2-取代-1,2-二氢喹啉类化合物的脱氢芳构化

Homogeneous Iridium-Catalyzed Dehydroaromatization of 2-Substituted-1,2-dihydroquinolines

采用原位制备的铱双膦(或膦氮)配合物在碘存在下催化2-取代-1,2-二氢喹啉、2-甲基2,3-二氢吲哚、1,4-二氢吡啶及3,4-二氢异喹啉等化合物的脱氢芳构化反应,并考察了不同金属前体、配体、催化剂用量、溶剂和碘等因素对反应速率和选择性的影响.结果表明,原位制备的[Ir(COD)Cl]2/(±)MeO Biphep在碘的存在下催化2-取代-1,2-二氢喹啉的脱氢芳构化反应速率快,选择性好,催化剂的用量少;对1,4-二氢吡啶和2,3-二氢吲哚的催化脱氢芳构化反应则须在高温下进行;而对3,4-二氢异喹啉,即使在加热回流条件下也只有不到5%的转化率.催化体系中碘的存在可以明显提高反应速率.

The dehvdroaromatization reactions of 2-substituted- 1, 2-dlhydroquinolines, 2-methyl-2,3-dihydroindole, 1,4-dihydropyridines and 3,4-dihydrolsoquinoline were investigated using iridium complexes with P-P or N-P ligands prepared in situ. The effect of different metal precursors, ligands, catalyst loading, solvents and iodine on the rate and selectivity for the dehydroaromatization was investigated using 2-methyl-1 2- dihydroquirioline as model substrate. The best result was achieved by using the complex [Ir(COD) Cl](2)/(±)-MeO-Biphep in the presence of iodine at room temperature. The aromatization of 2,3-dihydroindole and 1, 4-dihydropyridine could proceed only at high temperature in the same catalyst system, and 3,4-dihydroisoquinoline could not be aromatized even at 120 ° C for 36 h. The presence of iodine could accelerate the reaction rate.