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Part-IResults and Discussion3.2 Synthesis of condensed pyrimidine intermediates.3.2.1 Synthesis of condensed 2-chloromethylpyrimidin-4(3H)-ones (IIi-xvii)The condensed 2-chloromethylpyrimidine-4(3H)-ones IIi-xvii were planned to besynthesized through the dry HCl gas catalyzed one pot condensation of the appropriate 2-amino-3-carbethoxy substrates Ii-xvii and chloroacetonitrile 22 as described in earlierreports on HCl gas catalyzed one pot condensation by Shishoo et al. 35-38 (Scheme-15)OOORNdry HCl gasNHNH 2Cl1,4-dioxane0-5 o C, 6-12 hrsNClR = CH 3 or C 2 H 522Scheme-15IIi-xviiThe proposed mechanism is as follows (Scheme-16);The interaction of the nitrile 22a with a lewis A + under anhydrous conditions leads to theformation of species 23, with enhanced electrophilicity. This enhanced reactivity ofnitriles towards nucleophiles in the presence of acids, particularly halogen acids is wellknown. This enhanced reactivityhas been appropriately exploited for the synthesisof condensed pyrimidines through their reaction with appropriate o-aminocarbonylcompounds (Ii-xvii).NNAR C N AR+ A + R22a 23Scheme-16Cyclization reactions with nitriles under acidic conditions presumably proceed via theformation of transient amidine intermediate 26 resulting from the reaction ofo-aminocarbonyl compounds with the protonated nitrile 24 or imidoyl halide intermediate25 (Scheme-17).78