Stereospecific Preparation of (<i>Z</i>)- and (<i>E</i>)-2,3-Difluoro-3-stannylacrylic Ester Synthons and a New, Efficient Stereospecific Route to (<i>Z</i>)- and (<i>E</i>)-2,3-Difluoroacrylic Esters<sup>1</sup>
作者:Yi Wang、Long Lu、Donald J. Burton
DOI:10.1021/jo0517949
日期:2005.12.1
The (Z)-2,3-difluoro-3-stannylacrylic ester is readily prepared from (Z)-1,2-difluorovinyltriethylsilane via stereospecific stannyl/silyl exchange with KF/(Bu3Sn)2O or Bu3SnCl in DMF at 70 °C. The corresponding (E)-2,3-difluoro-3-stannylacrylate is prepared by stereospecific carbonylation of (E)-1,2-difluorovinyl iodide followed by low temperature/in situ stannylation of the resultant (Z)-2,3-difluoroacrylic
(Z)-2,3-二氟-3-锡烷基丙烯酸酯很容易由(Z)-1,2-二氟乙烯基三乙基硅烷与DMF中的KF /(Bu 3 Sn)2 O或Bu 3 SnCl进行立体定向的苯乙烯基/甲硅烷基交换而制得。在70°C下。相应的(E)-2,3-二氟-3-锡烷基丙烯酸酯是通过(E)-1,2-二氟乙烯基碘的立体定向羰基化反应,然后将所得的(Z)-2,3-进行低温/原位甲锡烷基化反应制得的二氟丙烯酸酯。用碘化铜(I)和钯(PPh 3)4催化,(Z)-和(E)-锡烷基丙烯酸酯容易在室温下与芳基碘化物和乙烯基溴化物以及2-碘噻吩偶联,以立体定向生成相应的(E)-和(Z)-2,3-二氟-3-芳基取代的丙烯酸酯或共轭二烯,收率高。