We describe herein a new protocol for the synthesis of 2,2′-((1S,1′S)-ethane-1,2-diylbis(phenylphosphanediyl))dibenzaldehyde ((S_P,S_P)-5), which is the key intermediate in the synthesis of macrocyclic iron(II)/(NH)₂P₂ catalysts for the highly enantioselective transfer hydrogenation of polar double bonds. The dialdehyde (S_P,S_P)-5 was obtained as a single diastereoisomer and enantiomer from an optically pure H-phosphinate in 33% yield over five steps. It was further converted to afford multigram quantities of the macrocyclic iron(II)/(NH)₂P₂ complexes, which were tested in the asymmetric transfer hydrogenation of aryl alkyl ketones and imines in 2-propanol on a 100 mmol scale. Ten substrates, including challenging ones such as tert-butyl phenyl ketone and industrially relevant molecules such as 3,5-bis(trifluoromethyl)acetophenone, were reduced in high yield (89.0–99.7%), excellent enantioselectivity (95.8–99.4% ee), and with low catalyst loadings (S/C up to 10 000/1).

中文翻译：

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大环铁（II）/（NH）₂ P ₂催化剂对极性双键的高对映选择性加氢

我们在本文中描述了合成2,2'-（（（1 S，1 'S）-乙烷-1,2-二基双（苯基膦二基））二苯甲醛（（S _P，S _P）-5）的新方案，是合成大环铁（II）/（NH）₂ P ₂催化剂的关键中间体，用于极性双键的高度对映选择性转移氢化。二醛（S _P，S _P）-5是由光学纯H制成的单一非对映异构体和对映体。-亚膦酸酯在五个步骤中的产率为33％。将其进一步转化以提供数克量的大环铁（II）/（NH）₂ P ₂配合物，该配合物在芳基烷基酮和亚胺在2-丙醇中的不对称转移氢化中以100 mmol的规模进行了测试。十种底物，包括具有挑战性的底物（如叔丁基苯基酮）和与工业相关的分子（如3,5-双（三氟甲基）苯乙酮），均降低了高收率（89.0–99.7％），出色的对映选择性（95.8–99.4％ee） ，并且催化剂用量低（S / C高达10000/1）。