We report a catalytic system comprised of nitrogen-centered di- or triphosphine ligands in conjunction with rhodium that is capable of delivering branched aldehydes from terminal olefin substrates which commonly give more linear aldehydes than branched. The incorporation of an apical nitrogen atom into the ligand backbone dramatically improves the reaction rate. Mechanistic and labeling studies suggest
我们报告了一种由以氮为中心的
二膦或三
膦配体与
铑结合组成的催化体系,该体系能够从末端烯烃底物中传递支链醛,而后者通常会比支链提供更多的线性醛。顶端氮原子结合到
配体主链中大大提高了反应速率。机理和标记研究表明,异常的选择性是由于与可逆的线性途径相比,Rh-烷基物质沿支化途径的不可逆捕获。通过高压原位NMR光谱观察到
铑物种的预催化平衡混合物,表明该平衡是催化静止状态。