Instituto de Investigaciones Químicas, CSIC and Universidad de Sevilla, Avda Américo Vespucio 49, Isla de la Cartuja, 41092 Sevilla, Spain.
J Org Chem. 2013 Apr 19;78(8):3997-4005. doi: 10.1021/jo400345v. Epub 2013 Mar 25.
The enantioselective catalytic hydrogenation of N-(3,4-dihydronaphthalen-2-yl) amides (1) with rhodium catalysts bearing phosphine-phosphite ligands 4 has been studied. A wide catalyst screening, facilitated by the modular structure of 4, has found a highly enantioselective catalyst for this reaction. This catalyst gives a 93% ee in the hydrogenation of 1a and also produces high enantioselectivities, ranging from 83 to 93% ee, in the hydrogenation of several OMe- and Br-substituted substrates. In contrast, the structurally related enol esters 2 are very reluctant to undergo hydrogenation. A coordination study of the representative enamide 1d has shown an unusual η(6)-arene coordination mode, over the typical O,C,C chelating mode for enamides, as the preferred one for this substrate in a Rh(I) complex. Deuteration reactions of 1c,d indicate a clean syn addition of deuterium to the double bond without an isotopic effect on the enantioselectivity.
手性膦-亚磷酸配体 4 负载的铑催化剂对 N-(3,4-二氢萘-2-基)酰胺 (1) 的对映选择性催化氢化进行了研究。通过 4 的模块化结构，进行了广泛的催化剂筛选，找到了一种对该反应具有高对映选择性的催化剂。该催化剂在 1a 的氢化中给出了 93%的对映体过量，并且在几个 OMe 和 Br 取代底物的氢化中也产生了高的对映选择性，范围从 83%到 93%ee。相比之下，结构相关的烯醇酯 2 非常不愿意进行氢化。对代表性烯酰胺 1d 的配位研究表明，在 Rh(I)配合物中，与典型的 O，C，C 螯合模式相比，该底物优先采用不寻常的 η(6)-芳族配位模式。1c，d 的氘代反应表明，氢在双键上以顺式加成，对映选择性没有同位素效应。
