Departamento de Química Orgánica, Facultad de Ciencias and Instituto de Síntesis Orgánica, Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain.
Chemistry. 2012 Feb 13;18(7):1969-83. doi: 10.1002/chem.201102426. Epub 2012 Jan 11.
A highly efficient Ru catalyst based on an achiral, very simple, and inexpensive amino alcohol ligand (2-amino-2-methylpropan-1-ol) has been developed for the asymmetric transfer hydrogenation (ATH) of chiral N-(tert-butylsulfinyl)imines. This complex is able to catalyze the ATH of both aromatic and the most challenging aliphatic sulfinylimines by using isopropyl alcohol as the hydrogen source. The diastereoselective reduction of aromatic, heteroaromatic, and aliphatic sulfinylketimines, including sterically congested cases, over short reaction times (1-4 h), followed by desulfinylation of the nitrogen atom, affords the corresponding highly enantiomerically enriched (ee up to >99 %) α-branched primary amines in excellent yields. The same ligand was equally effective for the synthesis of both (R)- and (S)-amines by using the appropriate absolute configuration in the iminic substrate. DFT mechanistic studies show that the hydrogen-transfer process is stepwise. Moreover, the origin of the diastereoselectivity has been rationalized.
一种高效的 Ru 催化剂，基于一种手性、非常简单且廉价的氨基醇配体（2-氨基-2-甲基-1-丙醇），已被开发用于手性 N-（叔丁基亚磺酰基）亚胺的不对称转移氢化（ATH）。该配合物能够通过使用异丙醇作为氢源，催化芳香族和最具挑战性的脂肪族亚磺酰亚胺的 ATH。通过短反应时间（1-4 h）对芳香族、杂芳族和脂肪族亚磺酰基酮亚胺进行非对映选择性还原，包括空间位阻较大的情况，随后对氮原子进行脱硫，可在极好的收率下得到相应的高对映体过量（ee 高达>99%）的α-支链伯胺。相同的配体对于使用亚胺底物中的适当绝对构型合成（R）-和（S）-胺同样有效。DFT 机理研究表明，氢转移过程是分步进行的。此外，还对非对映选择性的起源进行了合理化。
