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We report here a method by which Ni-nanoparticles can be used efficiently to catalyze the acetylation of a variety of amines and thiols under ambient conditions at room temperature. However in a competitive reaction, the thiol was acetylated selectively while the amine remained almost unaffected. The demonstrated chemoselectivity could have multiple potential synthetic applications. Some of the major advantages of this method are high yields, selectivity, short reaction times (<40 min), ease of operation, and compatibility with other protecting groups. Additionally, the process reported is environmentally benign. [ABSTRACT FROM AUTHOR]

Abstract: Use of highly monodispersed, easily recyclable and cheap nickel nanoparticles for oxidative coupling of aliphatic, aromatic, cyclic and heteroaromatic thiols to their corresponding disulfides has been reported. Ni-nanoparticles act as a green catalyst that can selectively catalyse oxidative coupling of thiols to disulfides without producing any over-oxidized products. The catalytic reaction occurred at room temperature with excellent yield under air atmosphere and high TON and TOF value could be achieved. Effect of solvent polarity and size distribution of the Ni-nanoparticles on the catalytic efficiency have been investigated. Nickel nanoparticles could be easily recovered by mild centrifugation. [Copyright &y& Elsevier]