Rh-Catalyzed CC Cleavage of Benzyl/Allylic Alcohols to Produce Benzyl/Allylic Amines or other Alcohols by Nucleophilic Addition of Intermediate Rhodacycles to Aldehydes and Imines
作者:Xi-Sha Zhang、Yang Li、Hu Li、Kang Chen、Zhi-Quan Lei、Zhang-Jie Shi
DOI:10.1002/chem.201201867
日期:2012.12.7
imines was slower than the CC cleavage and the equilibrium between the rhodacycle and phenylpyridine; iv) the whole transformation was a combination of two sequences of CC cleavage/nucleophilic addition and CC cleavage/protonation/CH activation/nucleophilic addition, with the latter being perhaps the main pathway. We also demonstrated the first example of cleavage of an C(alkenyl)C(benzyl) bond
我们报告了三种转化:1)从联芳基甲醇直接转化为联芳基甲胺;2)从一种联芳基甲醇直接转化为另一种联芳基甲醇;3)从烯丙基醇直接转化为烯丙基胺。这些变换是基于吡啶基定向的Rh催化的Ç 仲醇的C键裂解和随后的除CX(X = N或O)的双键。反应条件简单,不需要添加剂。C的驱动力C键裂解是稳定的rhodocycle中间体的形成。也可以使用其他定向基团,例如吡唑基,尽管其效率不如吡啶基。我们对转化1进行了深入研究,发现:1)底物范围广,富含电子的醇和缺乏电子的亚胺更有效;2)作为离去基团,醛对CC键断裂或整个转化均无显着影响;3)机理研究(中间分离,原位NMR光谱研究,竞争反应,同位素标记实验)表明:i)C在这些条件下,C裂解非常有效。ii)在rhodocycle中间体与质子化副产物苯基吡啶之间存在平衡;iii)所述rhodacycle中间体亚胺的添加步骤是比C慢 Ç裂解和rhodacycle和苯基之间的平衡;