Regioselective Synthesis of Pyrimidines from Ketene Dithioacetals or Alkoxymethylene Compounds
摘要:
Regioselective cyclizations of the condensation products obtained by the reaction of nitrogen nucleophiles with ketene dithioacetals or alkoxymethylene compounds are reported. Stereoelectronic factors or geometry of the carbon-carbon double bond determine the regioselectivity of heterocyclization processes.
The NMR spectra of α-cyano-β-amino-β-alkylacrylic esters prepared from α-cyano-β-methoxy-β-alkylacrylic esters and simple amines have been studied. It has been found that these aminoesters, in a variety of solvents, are all present in an intramolecular hydrogen-bonded enamine form with a chelate ring.