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Part-IResults and DiscussionYR 1XR 1N+XCNS2 o or 3 o amineR 2SNH 2R 2Y = N or OR 1 , R 2 = H, alkyl, aryl, cycloalkyl, hetarylX= CN, COOMe, COOEt, COPh, CO-hetaryl, CONH 2Scheme-6Sabnis and Rangekar 25,26 have developed the synthesis of versatile synthons in more than90% yield by condensing diethyl acetonedicarboxylate with sulphur and an activatedacetonitrile (Scheme-7). These compounds have demonstrated tremendous application insynthesizing novel dyes and many biologically active compounds.EtOOCEtOOCO+XCNS2 o or 3 o amineEtOOCEtOOCSXNH 2X = CN, COOEtScheme-7In the present work, two different variants have been used to prepare thiophene-o-aminoesters (Ii-xii)Method AIt is one pot condensation reaction involving reaction of ketone, ethylcyanoacetate andsulphur in the presence of diethylamine as catalyst at ambient temperature (method4.1.1b). Secondary amine used here is 0.5-1.0 mole equivalent of the amount of nitrileused (Scheme-8).Method BOR 2 + C 2 H 5 OOC CNR 1S 8DiethylamineScheme 8R 1R 2 COOC 2 H 5This method is two-step process (method 4.1.1b). First step is the prior condensation ofketone with an ethylcynoacetate, under the catalysis of sodium acetate to obtain an α,βunsaturatednitrile (Knoevenagel condensation product which is otherwise known asalkylidine intermediate) in a suitable solvent like benzene. In this step, water moleculesSIi-ivNH 270