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An efficient method for the preparation of 1,3-dithiolanes of aliphatic and both activated and deactivated aromatic carbonyl compounds with 1,2-ethanedithiol in the presence of a catalytic amount of inexpensive, easily recyclable, monodispersed, chemoselective Ni-nanoparticles having high TON and TOF is reported. An efficient method for the chemoselective thioacetalization of ketones in the presence of aldehydes using Ni-nanoparticles is also reported in this article. Our reaction is kinetically controlled and the method is relatively expedient, avoids the use of cost-prohibitive reagents, high temperatures and leads to excellent yield. Selective Protection of Carbonyl Compounds Over Nano-sized Nickel Catalysts Ajeet Kumar,a Santosh Kumar,a Amit Saxena,a Arnab De,b Subho Mozumdara* aDepartment of Chemistry, University of Delhi, Delhi, 110007, India; b Department of Chemistry, Indiana University, Bloomington, USA; subhoscom@yahoo.co.in An efficient method for the preparation of 1,3-dithiolanes of aliphatic and both activated and deactivated aromatic carbonyl compounds with 1,2-ethanedithiol in the presence of a catalytic amount of inexpensive, easily recyclable, monodispersed, chemoselective Ni-nanoparticles having high TON and TOF is reported. We report an efficient method for the chemoselective thioacetalization of ketones in the presence of aldehydes using Ni-nanoparticles. Our reaction is kinetically controlled and the method is relatively expedient, avoids the use of cost-prohibitive reagents, high temperatures and leads to excellent yield. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: Biologically active quinoxalines were efficiently synthesized in excellent yields and in less reaction time using inexpensive, monodispersed and easily recyclable Ni-nanoparticles. In order to elucidate the role of the Ni-nanoparticles, a control reaction was conducted using glyoxal and o-phenylenediamine in acetonitrile in the absence of Ni-nanoparticles. Quinoxaline was formed in around 10h with a 30% yield. However, the same reaction carried out in acetonitrile using 10mol% of Ni- nanoparticles (14–18nm) at 25°C and stirred under N2 gave quinoxaline in quantitative yield in 10min. The separation of the product was facile and the catalyst could be separated and recycled by mild centrifugation. Our method is very quick, avoids the use of expensive reagents, high temperatures (our reaction takes place at room temperature) and leads to excellent yield. [Copyright &y& Elsevier]