This invention aims at providing a catalyst for producing an optically active aldehyde or an optically active ketone, which is an optically active carbonyl compound, by carrying out selective asymmetric hydrogenation of an α,β-unsaturated carbonyl compound, particularly a catalyst which is insoluble in a reaction mixture for obtaining optically active citronellal which is useful as a flavor or fragrance, by carrying out selective asymmetric hydrogenation of citral, geranial or neral; and a method for producing a corresponding optically active carbonyl compound. The invention relates to a catalyst for asymmetric hydrogenation of an α,β-unsaturated carbonyl compound, which comprises a powder of at least one metal selected from metals belonging to Group 8 to Group 10 of the Periodic Table, or a metal-supported substance in which at least one metal selected from metals belonging to Group 8 to Group 10 of the Periodic Table is supported on a support, an optically active cyclic nitrogen-containing compound and an acid.
B(C6F5)3-Catalyzed tandem cyclization/hydrosilylation for the step-economical construction of 1,2,3,4-tetrahydroquinoxalines from readily available starting materials has been developed.
B(C6F5)3催化的串联环化/氢硅烷化反应,可从易得的起始物构建1,2,3,4-四氢喹啉。
(S)-Mandelate-Mediated Dynamic Kinetic Resolution of α-Bromo Esters for Asymmetric Syntheses of Aminoflavones, Dihydroquinoxalinones and Dihydrobenzoxazinones
作者:Yong Sun Park、Yoon Min Lee
DOI:10.3987/com-09-11700
日期:——
(S)-Mandelate-mediated dynamickineticresolution of α-bromoesters in nucleophilicsubstitution reaction has been investigated. Reactions of various aryl amine nucleophiles in the presence of TBAI and DIEA can provide the substitution products 2 and 7-19 up to 95% yield and 96:4 dr. Also, the simple procedure with spontaneous removal of the chiral auxiliary provides a practical protocol for asymmetric
L-Lactate-mediated Dynamic Kinetic Resolution of α-Bromo Esters for Asymmetric Syntheses of α-Amino Acid Derivatives
作者:Yelim Kim、Kon Ji Park、Yun Soo Choi、Myung-Su Lee、Yong Sun Park
DOI:10.5012/bkcs.2013.34.8.2531
日期:2013.8.20
effective for the dynamic resolution of α-halo esters. 3 In our continuous efforts to develop L-lactic acid as a chiral auxiliary for the dynamic resolution, we have recently found successful results with ethyl L-lactate. We herein report ethyl L-lactate-mediated dynamickinetic resolution of α-bromo esters for the asymmetric preparation of α-amino acid derivatives. Treatment of racemic α-bromo-α-phenylacetic
The sturdy chelation of 1,2-diamines and transition-metals would retard or even interrupt the routine catalytic cycles. In the amidation and asymmetric reductive amination (ARA) cascade reactions of diamines and ketoesters, we deployed sets of additives to ensure a smooth transformation catalyzed by the complexes of rhodium and versatile and highly modular phosphoramidite-phosphine ligands. The tunability