Rhodium catalyzed hydroformylation of β-pinene and camphene: effect of phosphorous ligands and reaction conditions on diastereoselectivity
作者:Humberto J.V. Barros、Maria L. Ospina、Eduardo Arguello、William R. Rocha、Elena V. Gusevskaya、Eduardo N. dos Santos
DOI:10.1016/s0022-328x(03)00098-6
日期:2003.4
effect of phosphorus ligands on the rhodium catalyzed hydroformylation of β-pinene and camphene has been studied. In unmodified systems, β-pinene undergoes a fast isomerization to α-pinene. At longer reaction times and higher temperatures, the isomerization equilibrium is shifted resulting in the 80% chemoselectivity for β-pinene hydroformylation products (97% trans). The addition of various diphosphines
研究了磷配体对铑催化β-pine烯和and烯的加氢甲酰化的影响。在未修饰的系统中,β-pine烯会快速异构化为α-pine烯。在更长的反应时间和更高的温度下,异构化平衡发生变化,导致β-pine烯加氢甲酰化产物的化学选择性达到80%(反式为97%)。各种二膦,膦或亚磷酸酯的添加可改善化学选择性并将加氢甲酰化反应转变为顺式醛3a。β-pine烯的加氢甲酰化反应的速率和非对映选择性都受辅助配体碱性的影响,但令人惊讶的是,对于锥角为128–165的配体,其立体特征与催化体系的非对映选择性之间没有相关性令人惊讶。 °。具有更多碱性配体的系统在β-pine烯加氢甲酰基化反应中显示出较低的活性,较高的非对映选择性和通常较高的化学选择性。在改性和未改性的体系中,systems烯都能生成线性醛6,几乎具有100%的区域选择性和化学选择性。磷配体的添加有利于内异构体6b:6a / 6b的形成≈1/ 1.