Hydrogen Bond Directed Highly Regioselective Palladium-Catalyzed Allylic Substitution
作者:Gregory R. Cook、Hui Yu、S. Sankaranarayanan、P. Sathya Shanker
DOI:10.1021/ja028426w
日期:2003.4.1
The palladium-catalyzed allylic substitution of 5-vinyloxazolidinones and derivatives was investigated. Unusual and high regioselectivity for the branched product was observed. The regioselectivity was influenced by the type of substrate, the solvents, and the nucleophile. Imide-type nucleophiles were found to be directed to the internal carbon (branched:linear, 75:25 to >98:2), whereas sulfonamides
研究了钯催化的 5-乙烯基恶唑烷酮和衍生物的烯丙基取代。观察到支化产物的异常和高区域选择性。区域选择性受底物类型、溶剂和亲核试剂的影响。发现酰亚胺型亲核试剂指向内部碳(支链:线性,75:25 至 >98:2),而磺酰胺、胺和丙二酸酯仅添加到烯丙基复合物的末端碳。相对非极性的溶剂如甲苯和四氢呋喃有利于支化产物(分别为 97:3 和 95:5)。乙腈和二氯甲烷提供较低的区域选择性(分别为 50:50 和 67:33),而质子溶剂乙醇的使用导致区域选择性的逆转(12:88)。基板上的导向组很重要。酰胺几乎完全形成支化产物,氨基甲酸酯得到区域异构体的 50:50 混合物,邻苯二甲酰亚胺作为亲核试剂。亲核试剂通过氢键定向的证据是通过用甲基取代酰胺的氢获得的,导致仅产生正常的线性产物。