通过铜催化氧化芳构化合成1,1'-联异喹啉

Synthesis of 1,1'-Biisoquinolines via Cu-Catalyzed Oxidative Aromatization

报道了一种合成1,1'-联异喹啉的实用新方法.N,N'-二苯乙基草酰胺(1a^1j)与三氯氧磷在氮气保护下于乙腈或甲苯中回流,发生Bischler-Napieralski环化反应生成3,3',4,4'-四氢-1,1'-联异喹啉(2a^2j).然后在二甲基亚砜(DMSO)溶剂中,以催化量的1,8-二氮杂双环[5,4,0]十一烯-7(DBU)为碱,化合物2a^2j在Cu(OAc)_2催化下与空气发生氧化芳构化反应,生成一系列1,1'-联异喹啉3a^3j,二步总收率为70%~88%.

A new method for practical synthesis of 1,1＇-biisoquinolines is described. Treatment of N,N＇-diphenethyloxal-amides （1a^1j） with phosphoryl trichloride in acetonitrile or toluene under N2 at reflux produced 3,3＇,4,4＇-tetrahydro-1,1＇-biisoquinolines （2a^2j） via Bischler-Napieralski cyclization. Subsequently, compounds 2a^2j underwent Cu（OAc）2-catalyzed aerobic oxidative aromatization in dimethyl sulfoxide （DMSO） in the presence of a catalytic amount of 1,8-diazabicyclo[5.4.0]undec-7-ene （DBU） to afford a series of 1,1＇-biisoquinolines （3a^3j） in 70%~88% overall yields （2 steps）.