Redox Reaction of the Pd0 Complex Bearing the Trost Ligand with meso-Cycloalkene-1,4-biscarbonates Leading to a Diamidato PdII Complex and 1,3-Cycloalkadienes: Enantioselective Desymmetrization Versus Catalyst Deactivation
作者:Vasily N. Tsarev、Dennis Wolters、Hans-Joachim Gais
DOI:10.1002/chem.200902739
日期:——
O‐nucleophiles and presumably proceeds through the hydrogen carbonate 17 b as key intermediate. The intermediate formation of 17 b is also indicated by the conversion of alcohol rac‐6 b to carbonate 12 b upon treatment with HCO3− and 1. The Pd0‐catalyzed desymmetrization of 5 b with formation of 12 b and its hydrolysis allow an efficient enantioselective synthesis of diol 13 b. The reaction of the seven‐membered
将Pd 0复杂1承载所述Trost配体2只经历一个浅显的氧化还原反应与1,4- biscarbonates图5b - d和外消旋- 22下形成diamidato -钯的II络合物7和相应的1,3-环二烯8b的– d。的复杂的氧化还原失活1在的反应占主导地位的通路5b的- d与HCO 3 -在室温下。但是,在0°C时六元碳酸氢盐5 b的复杂的催化量的1,和HCO 3 -主要反应在烯丙基烷基化,而导致衬底的高度选择性和desymmetrization醇,得到图6b与≥99% ee值在66%的产率。在反应中的催化剂负载量的增加5b中与1和HCO 3 - ,得到双环碳酸12b的(96% ee值,92%)。碳酸酯的形成12b中涉及π烯丙基钯的两个连续间和分子内取代反应II络合物16b的和18b的分别与O-亲核试剂一起,大概通过碳酸氢盐17b作为关键中间体。的中间形成部17b也由醇的转化率表示外消