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>Synthesis of polysubstituted 1,3-cyclohexadienes from β-branched α,β-alkenals and monoesters of ylidenemalonic acids
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Synthesis of polysubstituted 1,3-cyclohexadienes from β-branched α,β-alkenals and monoesters of ylidenemalonic acids
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机译:Synthesis of polysubstituted 1,3-cyclohexadienes from β-branched α,β-alkenals and monoesters of ylidenemalonic acids
3-Methyl- and 3-phenyl-2-butenal react with monoesters of alkylidene-, alkenylidene-, and arylmethylenemalonic acids in the presence of piperidine as the catalyst to give esters of 4,6-disubstituted 1,3-cyclohexadienecarboxylic acids in 23–96 yields. Under the same conditions cyclohexylideneacetic aldehyde reacts with the monoesters of prenylidene- and benzylidenemalonic acid to afford mixtures of 1,8a-trans- and 1,8a-cis-isomers of 1-substituted alkyl 1,5,6,7,8,8a-hexahydronaphthalene-2-carboxylates, the ratios and configurations of which were determined by means of1H NMR spectroscopy. In some cases the formation of cyclic dienes is impeded by the competing process of decarboxylation of acidic ylidenemalonates. The derivatives of 4,6-diphenyl-1,3-cyclohexadienecarboxylic acid were shown to be convenient precursors for the preparation ofmeta-terphenyl
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