Cu
<sup>II</sup>
‐Catalyzed Asymmetric Hydrosilylation of Diaryl‐ and Aryl Heteroaryl Ketones: Application in the Enantioselective Synthesis of Orphenadrine and Neobenodine
作者:Yao‐Zong Sui、Xi‐Chang Zhang、Jun‐Wen Wu、Shijun Li、Ji‐Ning Zhou、Min Li、Wenjun Fang、Albert S. C. Chan、Jing Wu
DOI:10.1002/chem.201200379
日期:2012.6.11
With certain amounts of sodium tert‐butoxide and tert‐butanol as additives, catalytic amounts of an inexpensive and easy‐to‐handle copper source Cu(OAc)2⋅H2O, a commercially available and air‐stable non‐racemic dipyridylphosphine ligand, as well as the stoichiometric desirable hydride donor polymethylhydrosiloxane (PMHS), formed a versatile in situ catalyst system for the enantioselective reduction
catalysts that feature only a single stereogenic element, yet this minimal chirality resource is demonstrated to be competent for effecting high levels of stereoinduction in the asymmetrictransferhydrogenation over a broad range of ketone substrates, including those that are not accommodated by known catalyst systems. The single stereogenic center of the (1-pyridine-2-yl)methanamine) is the only point-chirality
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, Absolute Configuration and Conformation of Some α-Aryl-2-pyridylmethanols
作者:Stefan E. Bojadziev、Dimiter T. Tsankov、Petko M. Ivanov、Nikolina D. Berova
DOI:10.1246/bcsj.60.2651
日期:1987.7
The syntheses of five optically active α-aryl-2-pyridylmethanols 1–5 are described. It is shown by means of chemical correlation with the known (−)-(αR,2S)-α-phenyl-2-piperidylmethanol 6 that all levo-rotatory isomers of 1–4 are of R configuration. It is also found via the relative integral intensities in the infrared spectra of the bands due to free and intramolecularly bonded hydroxyl groups in the