Wadhwa Kuldeep, Chintareddy Venkat Reddy, Verkade John G
Department of Chemistry, 1275 Gilman Hall, Iowa State University, Ames, Iowa 50011, USA.
J Org Chem. 2009 Sep 4;74(17):6681-90. doi: 10.1021/jo9012332.
Proazaphosphatrane P(PhCH(2)NCH(2)CH(2))(3)N (1a) is an efficient catalyst for the addition of aryl trimethylsilyl alkynes to a variety of aromatic, aliphatic, and heterocyclic aldehydes in THF at room temperature. The reaction conditions are mild and employ a low catalyst loading (ca. 5 mol %). Only propargylic alcohols were isolated in good to excellent isolated yields when electron-rich, electron-neutral, heterocyclic, and aliphatic aldehydes were employed, whereas beta-branched Morita-Baylis-Hillman (MBH) type adducts were isolated with electron-deficient aromatic aldehydes after conventional acid hydrolysis of the TMS ether products. Alkynes containing heterocyclic and aromatic groups bearing electron-withdrawing or -donating substituents underwent clean addition to cyclohexanecarboxaldehyde and to electron-rich aromatic aldehydes to give propargylic alcohols in excellent isolated yields. beta-Branched Morita-Baylis-Hillman (MBH) type adducts were isolated when electron-deficient aromatic aldehydes were employed. Reaction pathways to both types of products are proposed.
原氮杂环磷三胺P(PhCH(2)NCH(2)CH(2))(3)N（1a）是一种高效催化剂，可在室温下于四氢呋喃中使芳基三甲基甲硅烷基炔烃与多种芳香族、脂肪族和杂环醛发生加成反应。反应条件温和，催化剂负载量低（约5 mol%）。当使用富电子、电子中性、杂环和脂肪族醛时，仅以良好至优异的分离产率得到炔丙醇；而对于缺电子芳香醛，在对TMS醚产物进行常规酸水解后，分离得到β-支链的森田-贝利斯-希尔曼（MBH）型加合物。含有带有吸电子或供电子取代基的杂环和芳香基团的炔烃能顺利与环己烷甲醛和富电子芳香醛发生加成反应，以优异的分离产率得到炔丙醇。当使用缺电子芳香醛时，分离得到β-支链的森田-贝利斯-希尔曼（MBH）型加合物。文中提出了这两种类型产物的反应途径。
