A one-pot, non-catalytic approach to 1,2,4-benzothiadiazine-1,1-dioxides |
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Authors: | Artem CherepakhaVladimir O Kovtunenko Andrey Tolmachev Oleg Lukin |
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Institution: | a National Taras Shevchenko University, ChemBioCenter, Volodymyrska St. 62, 01033 Kiev, Ukraine b Enamine Ltd., A. Matrosova St. 23, 01103 Kiev, Ukraine |
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Abstract: | Condensations of o-halo-substituted benzenesulfonyl chlorides with 2-aminopyridines and amidines may give the corresponding 1,2,4-benzothiadiazine-1,1-dioxides under mild, non-catalytic conditions in nearly quantitative yields. The successful one-pot cyclization depends on three factors: (i) the nature of the o-halogen, (ii) the electronic character of the benzene ring substituent, and (iii) the steric load around the amidine unit. O-Fluorobenzenesulfonyl chlorides bearing methylcarboxyl- or nitro-group and o-chloro- and o-bromobenzenesulfonyl chlorides bearing nitro-group are reactive enough to give the desired 1,2,4-benzothiadiazine-1,1-dioxides in a one-pot base-promoted reaction. In all other cases, open-chain sulfonylated amidine intermediates are isolated. The latter are converted to the title compounds either in the presence of potassium carbonate or upon the addition of a copper(I) catalyst. |
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Keywords: | 1 2 4-Benzothiadiazine-1 1-dioxide Sulfonyl chlorides Amidines One-pot synthesis |
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