Highly Enantioselective Transfer Hydrogenation of Ketones with Chiral (NH)<sub>2</sub>P<sub>2</sub>Macrocyclic Iron(II) Complexes
作者:Raphael Bigler、Raffael Huber、Antonio Mezzetti
DOI:10.1002/anie.201501807
日期:2015.4.20
Bis(isonitrile) iron(II) complexes bearing a C2‐symmetric diamino (NH)2P2 macrocyclic ligand efficiently catalyze the hydrogenation of polar bonds of a broad scope of substrates (ketones, enones, and imines) in high yield (up to 99.5 %), excellent enantioselectivity (up to 99 % ee), and with low catalyst loading (generally 0.1 mol %). The catalyst can be easily tuned by modifying the substituents of
带有C 2对称的二氨基(NH)2 P 2大环配体的双(异腈)铁(II)络合物可以高产率(上)高效催化广泛范围内底物(酮,烯酮和亚胺)的极性键氢化。至99.5%(99.5%ee),优异的对映选择性(高达99%ee),并且催化剂负载量低(通常为0.1 mol%)。通过修饰异腈配体的取代基可以容易地调节催化剂。
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internal motions in a number of di-, tri- and tetraalkylhydrazines and to measure the corresponding free energies of activation. In particular, tetramethylhydrazine (Me2N-NMe2) was found to have, at - 150°, two pairs of diastereotopic methyls : this is due to the fact that both N-inversion and N,N-rotation are slow at this temperature and that a gauche conformation is adopted. The observed barrier (6.0 kcal
低温NMR光谱使我们可以“冻结”许多二,三和四烷基肼中的某些内部运动,并测量相应的活化自由能。特别地,发现四甲基肼(Me 2 N-NMe 2)在-150°下具有两对非对位甲基:这是由于在该温度下N反转和N,N旋转均很慢的事实并且采用了gauche构象。观察到的势垒(6.0kcal mol -1)归因于N,N-旋转,由于N-反转引起的势垒较高,并且在伴随快速旋转的情况下不能通过NMR测量。在其他情况下,尤其是Pr i MeN-NH 2,Me 2N-NPr i 2和Pr i 2 N-NHMe,检测到两个不同的运动(反转和旋转)。在Me 2 N-NHMe的情况下,还可以观察到由在低温下变为手性的胺氮诱导的氮键合甲基(Me 2 N)的等时性行为的第一个例子。