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.
A new chiral bicyclic guanidine-catalyzed direct catalytic aldolreaction of 5H-oxazol-4-ones with aldehydes has been developed. The present aldolreaction proceeds smoothly with high enantioselectivity using bicyclic guanidines bearing a hydroxy group at the appropriate position, and various combinations of 5H-oxazol-4-ones and aldehydes are applicable. The method provides synthetically useful alpha
The Influence of Substituents on the Hydroxyl-Bearing Carbon in the Aza-Payne Rearrangement of Aziridinemethanols
作者:Wenjin Xu、Jun Zhang、Hao Guo、Qifeng Zhu、Xianming Hu
DOI:10.2174/157017809788681310
日期:2009.7.1
A new series of α,α-disubstituted aziridinemethanols have been synthesized and their aza-Payne rearrangement reactions were studied. The results show that α,α-disubstituted aziridinemethanols with electron-withdrawing groups accelerate the aza-Payne rearrangement than those with electron-donating groups. All of the rearrangements proceeded through an inversion of configuration at the C-2 carbon.
system is applied to the analysis of opticallyactive species responding to cases of self-disproportionation of enantiomers (SDE) by sublimation. The fundamentals behind the observed phenomenon led to an advanced concept of enantiomers recognition based on selective sublimation. The work shows how mechanochemistry aids the acceleration of the naturally occurring phenomena and how the mechanical promotion
Aziridin-2-yl methanols as organocatalysts in Diels–Alder reactions and Friedel–Crafts alkylations of N-methyl-pyrrole and N-methyl-indole
作者:Bianca F. Bonini、Elena Capitò、Mauro Comes-Franchini、Mariafrancesca Fochi、Alfredo Ricci、Binne Zwanenburg
DOI:10.1016/j.tetasy.2006.11.028
日期:2006.11
A series of enantiomerically pure aziridin-2-yl methanols have been synthesized from aziridine-2-carboxylic esters and have been tested as organocatalysts in Diels-Alder reactions and Friedel-Crafts alkylations of N-methyl-pyrrole and N-methyl-indole using alpha,beta-unsaturated aldehydes. Moderate to good ee's have been obtained. The coupling of N-methyl-pyrrole with crotonaldehyde and cinnamaldehyde using (2S,3S)-3-methylazirin-2-yl(diphenyl)methanol TFA salt as the catalyst gave the best results (ee 75%). (c) 2006 Elsevier Ltd. All rights reserved.