Available 2-acylamino-3,3-dichloroacrylonitriles I are important reagents in the synthesis of 1,3-azole derivatives [133]. In the present work we showed that reagents I can be applied for preparing polyfunctional thiophenes II.The structure of compounds II was confirmed by their 1 H and IR spectra, as well as by the fact that many substrates containing the O=C3CH 2 3S3C=C3C=N g g g ment undergo a similar cyclization [4,5].Treatment of substituted thiophenes II with concentrated sulfuric acid gives rise to intramolecular transacylation with subsequent annelation of the 2-oxo-2,3-dihydro-1H-1,4-thiazine system to the thiophene ring, which follows from spectral and mass spectral data.Methyl 4-acylamino-3-amino-5-(methoxycarbonylmethylsulfanyl)thiophene-2-carboxylates IIa and IIb. To a solution of 0.004 mol of nitrile Ia or Ib in 30 ml of absolute methanol, 0.0082 mol of methyl
Addition products of carboxylic acid amides and trichloroacetaldehyde are readily converted into 3-arylsulfanyl-2-acylamino-3-chloroacrylonitriles which react with hydrazine hydrate to afford 3(5)-amino-5(3)-arylsulfanyl-4-acylaminopyrazoles. The presence of an amidine fragment in the latter makes them capable of undergoing cyclocondensations with b-dicarbonyl compounds and ethyl cyanoacetate.
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