(R)-Benzoins and (R)-2-hydroxypropiophenone derivatives are formed on a preparativescale by benzaldehyde lyase (BAL)-catalyzed C−C bond formation from aromatic aldehydes and acetaldehyde in aqueous buffer/DMSO solution with remarkable ease in high chemical yield and highopticalpurity. The substrate range of this thiamin diphosphate-dependent enzyme was examined with respect to a broad applicability
Thiaminediphosphatedependentenzymes are well known for catalyzing the asymmetricsynthesis of chiral α‐hydroxy ketones from simple prochiral substrates. The steric and chemical properties of the enzyme active site define the product spectrum. Enzymes catalyzing the carboligation of aromatic aldehydes to (S)‐benzoins have not so far been identified. We were able to close this gap by constructing
N′-dioxide complex as catalyst. This strategy provided an array of optically active 2-acyl-2-hydroxy cyclohexanones in moderate to good yields with high enantioselectivities. The asymmetric isomerizations of acyclic α-hydroxy aldehydes and α-iminols were achieved as well under modified conditions, affording the corresponding chiral α-hydroxy ketones and α-amino ketones in moderate results. Moreover, further
Base-Free Asymmetric Transfer Hydrogenation of 1,2-Di- and Monoketones Catalyzed by a (NH)<sub>2</sub>
P<sub>2</sub>
-Macrocyclic Iron(II) Hydride
作者:Lorena De Luca、Antonio Mezzetti
DOI:10.1002/anie.201706261
日期:2017.9.18
Base? No thanks! A hydride isonitrile iron(II) complex bearing a C2-symmetric diamino (NH)2P2 macrocyclic ligand catalyzes the asymmetric transferhydrogenation of ketones under base-free conditions with excellent enantioselectivity (up to 99 % ee). Base-labile benzoins are formed from the corresponding benzils with up to 95 % ee.
根据?不用了,谢谢!带有C 2对称二氨基(NH)2 P 2大环配体的氢化物异腈铁(II)络合物在无碱条件下催化酮的不对称转移氢化,具有出色的对映选择性(最高99%ee)。碱不稳定的安息香由相应的苯构成,其ee最高可达95%。
Benzaldehyde Lyase-Catalyzed Direct Amidation of Aldehydes with Nitroso Compounds
作者:Peruze Ayhan、Ayhan S. Demir
DOI:10.1002/adsc.201000735
日期:2011.3.7
furnishes N‐arylhydroxamic acids in high yields. Aromatic aldehydes and benzoins are converted into enamine‐carbanion‐like intermediates prior to their reaction with nitroso compounds. The kinetic resolution of rac‐2‐hydroxy‐1,2‐diphenylethanones furnished (S)‐benzoins and arylhydroxamic acids with high enantioselectivities and conversions.