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Part-IResults and DiscussionOOEtNHOXIi-xviNH 224(IVa)CH 2 ClOEtNH 2OXNOEtNH26 CH 2 ClXIi-xviNH 2Cl25CH 2 ClONHClXIIi-xviiNScheme-17X = S or -CH=CH-The imidoyl halide intermediate enhances the electrophilicity of the nitrile carbontremendously and thus, helps in their facile condensation with the aminocarbonylcompounds. This is then followed by intramolecular cyclization. 36 This cyclization is alsoprobably facilitated by the protonation of the carbonyl group.For the condensation of 2-amino-3-carbethoxy substrate with nitriles under the influenceof dry HCl gas, some productive modification in experimental procedure has been tried,that involves the mixing the two reactants in saturated solution of HCl in dioxane (7M)and stirring the mixture for few hrs at 0-5 o C, followed by further stirring for 2 hrs at RTand thereafter heating on a boiling water-bath for 2 hrs. The reaction mixture was thenworked up as usual, involving pouring on ice-water mixture and basification with conc.ammonium hydroxide. This modification not only reduced the reaction time and labourbut also gave excellent yields of the desired products. In fact only once a stock solution ofdioxane saturated with HCl was to be prepared and then it could be used simultaneouslyfor 4-5 different condensations at a time. This has also curtailed the use of multiple HClgeneration assemblies.79