Environmentally benign approach towards C-S cross-coupling reaction by organo-copper(II) complex.

C-S cross-coupling reaction in water giving an excellent yield of the desired C-S coupled product by using a newly developed Bis[2-(4,5-diphenyl-1H-imidazol-2-yl)-4-nitrophenolato] copper(II) dehydrate complex as catalyst. Although it was the first report of the synthesis of such a novel organo-copper complex from our laboratory, its potential catalytic application was not tested so far. Keeping this in mind and based on our anticipation, we developed a greener route for the C-S coupling reaction. The result is very interesting and comprises the subject matter of this report.

One-pot three-component tandem annulation of 4-hydroxycoumarine with aldehyde and aromatic amines using graphene oxide as an efficient catalyst.

A convenient and efficient solvent-free, facile, one-pot three-component graphene oxide catalysed approach has been described for the synthesis of chromeno-[4,3-b]quinolin-6-one derivatives from 4-hydroxycoumarin with aldehydes and aromatic amines. Graphene oxide (GO) has proved to be a new class of heterogeneous carbocatalyst which could be easily recovered and reused up to 5th run without significant loss of its catalytic activity. A broad scope of substrate applicability is offered and a plausible mechanism is also suggested for this developed protocol.