l-Proline as an efficicent catalyst for the multi-component synthesis of 6-amino-4-alkyl/aryl-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles in water

An efficient four-component synthesis of 6-amino-4-alkyl/aryl-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles involving ethyl acetoacetate, hydrazine hydrate, malononitrile, and various aldehydes using l-proline (10 mol %) in water under mild reaction condition in excellent yields is established. A comparative study of l-proline with γ-alumina, basic alumina, and KF-alumina was also carried out. The generality and functional tolerance of this convergent and environmentally benign method is demonstrated.     

Reaction of selenium dioxide with aromatic ketones in the presence of boron triflouride etherate: a protocol for the synthesis of triarylethanones

An efficient regioselective protocol for the C-C bond formation by the unexpected α,α-diarylation of aromatic ketones with unactivated arenes in the presence of selenium dioxide and boron trifluoride etherate has been developed. The generality and functional tolerance of this protocol is demonstrated by the synthesis of a series of triarylethanones.     

One-pot synthesis of unsymmetrical benzils from aryl methyl ketones and arenes in the presence of selenous acid catalysed by p-toluenesulfonic acid monohydrate

A modified one-pot method for the synthesis of unsymmetrical and heteroaryl benzils from substituted acetophenones and unactivated or weakly activated arenes by the use of H₂SeO₃ and p-TsOH·H₂O as catalysts at 35 °C is established. The present method is regioselective and avoids the use of p-TsOH·H₂O in stoichiometric amount in the presence of H₂SeO₃ and afforded unsymmetrical benzils in good yields.