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
The enantioselective benzoin condensation promoted by chiral triazolium precatalysts: stereochemical control via hydrogen bonding
作者:Sarah E. O'Toole、Stephen J. Connon
DOI:10.1039/b908517c
日期:——
The design of a newclass of triazolium ion precatalysts incorporating protic substituents is described. These materials promote the enantioselective benzoincondensation of a range of aromatic aldehydes (1–62% ee). Catalyst evaluation studies strongly support the involvement of hydrogen bond donation by the catalyst in the stereocentre-forming step of the catalytic cycle.
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%。
Biocatalyzed asymmetric reduction of benzils to either benzoins or hydrobenzoins: pH dependent switch
作者:Mohan Pal、Gautam Srivastava、Amar Nath Sharma、Suneet Kaur、Ravinder S. Jolly
DOI:10.1039/c5cy00158g
日期:——
synthesis. Biocatalytic reduction of benzils is a straightforward approach to prepare these molecules. However, known methods are not selective and lead to formation of a mixture of benzoin and hydrobenzoin, requiring expensive separation procedures. Here, we describe an enzyme system Talaromyces flavus, which exhibited excellent pH dependent selectivity for the conversion of benzil to either benzoin or
Chiraltriazolium salts bearing a pyridine ring were developed as N-heterocyclic carbene precursors. In the presence of the chiraltriazoliumsalt and a base, the catalytic asymmetricbenzoin condensation proceeded to afford the product in high level of chemical yield and enantioselectivity. A wide range of aromatic aldehydes were applicable to this reaction.