Collect. Czech. Chem. Commun. 1981, 46, 3115-3121

Study of keto-enol tautomerism and alkylation reactions of β-ketosulphones of 5-nitrofuran series

Adolf Jurášek, Dana Polakovičová and Jaroslav Kováč

Department of Organic Chemistry, Slovak Institute of Technology, 880 37 Bratislava


2-(5-Nitro-2-furyl)-2-oxoethyl 3-X-phenyl sulphones I react with diazomethane in tetrahydrofuran or dioxane to give trisubstituted ethylenes II, i.e. 1-(5-nitro-2-furyl)-1-methoxy-2-(4-X-phenylsulphonyl)ethylenes (X = H, CH3, OCH3, N(CH3)2, Cl, NO2) which have Z configuration. From results of spectral and chemical investigation it follows that β-ketosulphones of 5-nitrofuran series only exist in ketoform and are very strong CH-acids (pKa 7.82-5.23). Alkylation of the sulphones I (X = H, CH3) with methyl iodide under conditions of extraction alkylation gives the corresponding C-methyl derivatives III. Interpretation is given of IR, UV, 13C and 1H NMR spectra of the sulphones I and II.