Competition between Alkenes in Intramolecular Ketene−Alkene [2 + 2] Cycloaddition: What Does It Take to Win?
作者:Guillaume Bélanger、François Lévesque、Julie Pâquet、Guillaume Barbe
DOI:10.1021/jo0483466
日期:2005.1.1
of developing a new synthetic methodology using ketenes in sequential cycloaddition steps, we were faced with a competition problem with molecules containing a ketene tethered to more than one reacting partner. To pinpoint the electronic and tethering requirements for a chemoselective reaction, we undertook a series of ketene−alkene [2 + 2] cycloaddition competition experiments. Those experiments were
在开发一种在连续环加成步骤中使用烯酮的新合成方法的过程中,我们面临着一个竞争问题,即含有与多个反应伙伴相连的烯酮的分子。为了确定化学选择反应的电子和束缚要求,我们进行了一系列乙烯酮-烯烃[2 + 2]环加成竞争实验。这些实验是在含有两个具有不同束缚长度的相同烯烃或两个具有相同束缚长度但在电子上不同的烯烃的分子上进行的。我们证明了形成五元环的反应比六元环的反应快得多,并且计算出的分子内烯酮-烯烃[2 + 2]环加成物的哈米特常数ρ为-1.39。