Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg (Germany), Fax: (+49) 6221-54-4205.
Chemistry. 2014 Jan 3;20(1):292-6. doi: 10.1002/chem.201303539. Epub 2013 Dec 20.
The conversion of simple, easily available urea-substituted 3-phenylpropargyl alcohols catalyzed by a simple IPr-gold(I) catalyst in a gold(I)-catalyzed cascade reaction composing of a gold-catalyzed nucleophilic addition and a subsequent gold-catalyzed substitution reaction delivers 1H-imidazo[1,5-a]indol-3(2H)-ones. Other gold(I) catalysts or silver catalysts gave lower yields and often gave other side products. Gold(III) and copper(II) catalysts decomposed the starting material. Twelve examples, including donor and acceptor substituents on the distal nitrogen of the urea substructure, are provided. An X-ray crystal structure analysis confirmed the structural assignment. The mechanistic investigation including isolation and further conversion of intermediates and reactions with enantiopure starting materials indicated that after the nucleophilic-addition step, the substrate undergoes an S(N)1-type benzylic substitution reaction at the indolyl alcohol intermediate or an intramolecular hydroamination reaction of the 2-vinylindole intermediate.
简单易得的尿素取代 3-苯基丙炔醇在简单的 IPr-金（I）催化剂作用下的转化，在金（I）催化的级联反应中进行，该反应由金催化的亲核加成和随后的金催化取代反应组成，生成 1H-咪唑并[1,5-a]吲哚-3(2H)-酮。其他金（I）催化剂或银催化剂产率较低，并且往往会生成其他副产物。金（III）和铜（II）催化剂会分解起始原料。提供了包括尿素亚结构远端氮上的给体和受体取代基的 12 个例子。X 射线晶体结构分析证实了结构分配。包括中间体的分离和进一步转化以及与手性纯起始原料的反应的机理研究表明，在亲核加成步骤之后，底物在吲哚醇中间体上经历 S(N)1 型苄基取代反应，或者在 2-乙烯基吲哚中间体上经历分子内氢胺化反应。
