A simple, mild and environment-friendly procedure has been developed for Knoevenagel condensation between aromatic aldehydes or ketones and malonic acid in the presence of tetrabutylammoniumbromide and K 2 CO 3 under microwave irradiation in water. The products are obtained in excellent yields and are in a state of high purity.

No abstract

No abstract

We report the total assignments of the 13 C and 1 H NMR spectra of some 4-methyl-2-oxo-(2H)-pyrido[1,2-a]pyrimidine and 2-methyl-4-oxo-(4H)-pyrido[1,2-a]pyrimidine derivatives. The products were characterized by 1 H and 13 C NMR and reported data for similar compounds. No comparative data for the two sets of isomeric compounds with respect to 13 C and 1 H NMR have been reported to date. We made some detailed studies of the 2D NMR spectra of these compounds and observed that assignments made for non-protonated carbon atoms by us and those reported in the literature for similar compounds need correction. The revised assignments were made on the basis of heteronuclear single quantum correlation (HSQC) and heteronuclear multiple bond correlation (HMBC) techniques.

No abstract