No abstract

Active methylene compounds are regioselectively dialkylated by variety of alkyl halides using cesium carbonate in quantitative yield. The reaction yielded exclusively dialkylated products with no intermediate monoalkyaltion or mixture of products.

A simple and economic synthesis of 3,4-dihydropyrimidin-2(1H)-ones using ammonium trifluoroacetate as catalyst and as solid support is accomplished. Easy workup procedure for the synthesis of title compounds is well arrived at and is well documented.

A simple, convenient, and industrially viable process for the isolation of 4-oxobutanoic acid derivatives resulting from Friedel−Crafts acylation products of aromatic hydrocarbons with succinic anhydride is reported. The isolation procedure involves simple quenching of the reaction mixture followed by filtration of the product in good yield and with excellent purity. The generality of the procedure has been demonstrated with representative examples of aromatic hydrocarbon precursors and has also been applied to the isolation of fenbufen. The quantity of aluminum chloride used in the reaction has also been optimized to reduce the load on effluent.

In the synthesis and process development of sibutramine (9), the isolation and characterization of two potential by-products namely heptane dinitriles (4a − b) and bis-cyclobutyl alkylamine (10) have been studied. The key steps in the synthesis of sibutramine which have contributed to the formation of above by-products are cycloalkylation of 4-chlorophenyl acetonitrile (1) and tandem Grignard reduction on 1-(4-chlorophenyl)cyclobutyl carbonitrile (3).