system with enantiomeric excesses up to 99.5%. Upon introduction of a readily removable ortho-bromo atom to the phenyl ring, enantiomerically enriched 4-chlorophenylpyridylmethanol was obtained by hydrogenation method with 97.3% ee, which provided an important chiral intermediate for some histamine H1 antagonists.
Preparation of pyridinyl aryl methanol derivatives by enantioselective hydrogenation of ketones using chiral Ru(diphosphine)(diamine) complexes. Attribution of their absolute configuration by 1H NMR spectroscopy using Mosher's reagent
provide highly efficient catalysts for enantioselectivehydrogenation of a series of pyridinyl aryl ketones. The hydrogenation proceeds under mild conditions providing chiral pyridinyl aryl methanol derivatives with consistently high yields and moderate to excellent enantioselectivities (up to 99% ee) according to the structure of the chiral diphosphine. NMR studies, based on Mosher's ester derivatisation
The RuPHOX-Ru catalyzedasymmetrichydrogenation of diaryl ketones has been established, providing the corresponding chiral diaryl methanols in up to 99% yield and 99% ee. The protocol could be performed on a gram-scale with a relatively low catalyst loading (2000 S/C) and the resulting products allow for several useful transformations, in particular for the synthesis of chiral drugs, such as, (S)-Orphenadrine
已经建立了 RuPHOX-Ru 催化的二芳基酮不对称氢化,以高达 99% 的产率和 99% ee 提供相应的手性二芳基甲醇。该方案可以在催化剂负载量相对较低 (2000 S/C) 的克规模上进行,所得产品可进行多种有用的转化,特别是用于手性药物的合成,例如 ( S ) -Orphenadrine和( S )-新苯二甲酸。氘标记和对照实验表明,RuPHOX-Ru 催化的不对称氢化完全以 H 2作为唯一氢源进行氢化。
Asymmetric Addition of Pyridyl Aluminum Reagents to Aldehydes Catalyzed by a Titanium(IV) Catalytic System of (<i>R</i>)-H<sub>8</sub>-BINOLate
The asymmetric addition of pyridyl aluminum reagents to aldehydes has been successfully developed by employing a titanium(IV) catalytic system of (R)-H-8-BINOLate, which affords a series of valuable optically active diarylmethanols containing various pyridyl groups in high yields with excellent enantioselectivities of up to 98% ee.