2,2,3-Trisubstituted Tetrahydrofurans and 2<i>H</i>-Tetrahydropyrans by Tandem Demethoxycarbonylation−Michael Addition Reactions
作者:Richard A. Bunce、Eric D. Dowdy、R. Shawn Childress、Paul B. Jones
DOI:10.1021/jo971600s
日期:1998.1.1
A tandem demethoxycarbonylation-Michael addition reaction has been developed as a synthetic route to highly functionalized five- and six-membered oxygen heterocycles. Methyl esters, activated toward decarboxylation by a C-2 ethoxycarbonyl group and tethered by a three- or four-atom chain to an acrylate Michael acceptor, have been prepared and used as the cyclization substrates. Treatment of these compounds
串联脱甲氧基羰基化-迈克尔加成反应已开发为合成高度官能化的五元和六元氧杂环的途径。已制备了被C-2乙氧基羰基活化而脱羧并通过三或四原子链束缚于丙烯酸酯Michael受体的甲酯,并将其用作环化底物。在DMEU(1,3-二甲基-2-咪唑啉酮)中用氯化锂在120摄氏度下处理这些化合物4-8小时,导致甲酯的化学选择性S(N)2脱烷基,脱羧和中间体的环化通过将迈克尔加成到侧垂丙烯酸酯部分而烯醇化。以60-90%的产率提供四氢呋喃和2H-四氢吡喃衍生物,非对映选择性高达7.5:1有利于具有C-2乙氧羰基基团反式至C-3乙酸酯侧链的产物。该反应最适合制备五元和六元环,并且环化反应最干净地从通过叔烯醇环化的底物进行。介绍了合成和机械细节。