【摘要】 报道了一种利用价廉易得的邻苯二胺衍生物与α-酮酸酯经环化/钌催化的亚胺和酰胺氢化串联反应一锅法制备1,2,3,4-四氢喹喔啉的方法.该方法使用原位生成的Ru（acac）₃/Triphos配合物和HBF₄共催化剂组成的催化体系,高效制备了一系列2-取代的1,2,3,4-四氢喹喔啉,官能团耐受性良好.在较低的氢气压力和不使用助催化剂的条件下,反应可停留在只生成3,4-二氢喹喔啉酮产物阶段.反应机理研究表明,钌催化剂仅用于还原亚胺和酰胺部分,而布朗斯台德酸助催化剂的选择对于酰胺部分去氧氢化至关重要.研究表明,布朗斯台德酸助催化剂通过活化酰胺部分参与催化过程.更多还原

【Abstract】 Efficient synthesis of 1,2,3,4-tetrahydroquinoxalines from readily available 1,2-diaminobenzenes and α-ketoesters via a one-pot tandem process that combines cyclization and Ru-catalyzed hydrogenation of imine and amide moieties is reported. Using the catalyst consisting of in situ generated ruthenium/triphos complex and HBF4 co-catalyst,a range of structurally diverse 2-substituted 1,2,3,4-tetrahydroquinoxalines were prepared in good to excellent yields,and various functional groups including those are reduction-sensitive were well tolerated. The reaction could stop at 3,4-dihydroquinoxalin-2(1 H)-one stage under a lower hydrogen pressure in the absence of any co-catalyst. Mechanistic studies revealed that the ruthenium catalyst works exclusively for the reduction of imine and amide moieties,and the choice of a Bronsted acid co-catalyst is crucialto the successful deoxygenative hydrogenation of amide moiety. It is believed that the activation of the amide moiety with the Bronsted acid co-catalyst is involved in the catalytic process.更多还原