Search results for "Selective reduction"
showing 7 items of 7 documents
ENANTIOSELECTIVE REDUCTION OF PROCHIRAL KETONES PROMOTED BY AMINO AMIDE RUTHENIUM COMPLEXES: A DFT STUDY
2021
International audience; The origin of enantioselectivity in the reaction of chiral Ru amino amide complexes in the asymmetric transfer hydrogenation of acetophenone was investigated using DFT calculations. For the most stable active catalysts, the full free energy profiles for the reaction were calculated according to the concerted hydrogen transfer mechanism. We succeeded in reproducing the experimentally observed enantioselectivity for the studied Ru amino amide complexes. Our results indicate that the high enantioselectivity can be explained by a stabilizing CH-π interaction existing between the phenyl group of acetophenone and the aromatic substituent of the catalyst, which plays a sign…
Über Hydroxy‐linolsäuremethylester und die Umsetzung von Linolsäuremethylester mit N‐Bromsuccinimid
1962
Hydroxy-linolsauremethylester wird durch selektive Reduktion von Linolsauremethylester-hydroperoxyd mit Na-Sulfit u. a. dargestellt. Die Autoxydation des Hydroxy-linolsauremethylesters verlauft nicht autokatalytisch und ist nach Aufnahme von 1 Mol Sauerstoff pro Mol Substanz nahezu beendet. Die Reaktionsprodukte sind relative niedermolekular. Die Reaktion von Linolsauremethylester mit N-Bromsuccinimid konnte durch Umsetzung des instabilen Reaktionsproduktes mit Silbernitrat weitgehend aufgeklart werden. About Hydroxy Methyl Linoleate and the Reaction of Methyl Linoleate with N-Bromosuccinimide Hydroxy methyl linoleate is prepared by selective reduction of methyl linoleate hydroperoxyde with…
Synthesis and gas chromatographic-mass spectrometric analysis of reduced compounds derived from 6 alpha- and 6 beta-hydroxy-11-deoxycorticosterone.
1989
Abstract A series of thirty two 6-hydroxylated steroids were synthesized by selective reduction of the 4–5 double bond, the 3-oxo group, and/or the 20-oxo group of 6α- and 6β-hydroxyDOC. The different reactions leading to the production of specific isomers are discussed. The gas chromatographic and spectrometric characteristics of the methoxime-trimethylsilyl (MO-TMS) or trimethylsilyl (TMS) derivatives of the isomers obtained are given. The gas chromatographic separation of the syn- and anti -isomers of the methoxime in position 3 was found to be characteristic of the configuration of the hydroxyl in position 6. The difference between methylene unit values of syn- and anti- isomers is much…
Evolution of small prokaryotic genomes
2015
As revealed by genome sequencing, the biology of prokaryotes with reduced genomes is strikingly diverse. These include free-living prokaryotes with ∼800 genes as well as endosymbiotic bacteria with as few as ∼140 genes. Comparative genomics is revealing the evolutionary mechanisms that led to these small genomes. In the case of free-living prokaryotes, natural selection directly favored genome reduction, while in the case of endosymbiotic prokaryotes neutral processes played a more prominent role. However, new experimental data suggest that selective processes may be at operation as well for endosymbiotic prokaryotes at least during the first stages of genome reduction. Endosymbiotic prokar…
Advances in selective conversions by heterogeneous photocatalysis
2010
Selective photocatalytic conversions are offering an alternative green route for replacing environmentally hazardous processes with safe and energy efficient routes. This paper reports the most recent advances in the application of heterogeneous photocatalysis to synthesize valuable compounds by selective oxidation and reduction.
Total Syntheses of Four Stereoisomers of 4α-Hydroxy-1β,7β-peroxy- 10βH-guaia-5-ene
2005
[reaction: see text]. The first total syntheses of four stereoisomers of 4alpha-hydroxy-1beta,7beta-peroxy-10betaH-guaia-5-ene are reported starting from the readily available (+)-dihydrocarvone. These compounds have been synthesized from dienes (-)-isoguaiene and (-)-10-epi-isoguaiene by tandem ene hydroperoxylation-[4 + 2] cycloaddition with O(2) followed by selective reduction. The structure of the natural 4alpha-hydroxy-1beta,7beta-peroxy-10betaH-guaia-5-ene isolated from Liabum floribundum has been confirmed.
Sequential Iron-Catalyzed C(sp2)–C(sp3) Cross-Coupling of Chlorobenzamides/Chemoselective Amide Reduction and Reductive Deuteration to Benzylic Alcoh…
2023
Benzylic alcohols are among the most important intermediates in organic synthesis. Recently, the use of abundant metals has attracted significant attention due to the issues with the scarcity of platinum group metals. Herein, we report a sequential method for the synthesis of benzylic alcohols by a merger of iron catalyzed cross-coupling and highly chemoselective reduction of benzamides promoted by sodium dispersion in the presence of alcoholic donors. The method has been further extended to the synthesis of deuterated benzylic alcohols. The iron-catalyzed Kumada cross-coupling exploits the high stability of benzamide bonds, enabling challenging C(sp2)–C(sp3) cross-coupling with alkyl Grign…