An efficient, chemoselective homologation of Weinreb amides to the corresponding variously substituted [small alpha]-oxyketones has been developed via the addition of lithiated [small alpha]-oxygenated species. This one-step, experimentally easy, high yielding protocol...
Sulfone Group as a Versatile and Removable Directing Group for Asymmetric Transfer Hydrogenation of Ketones
作者:Vijyesh K. Vyas、Guy J. Clarkson、Martin Wills
DOI:10.1002/anie.202004658
日期:2020.8.17
The sulfone functional group has a strong capacity to direct the asymmetrictransferhydrogenation (ATH) of ketones in the presence of [(arene)Ru(TsDPEN)H] complexes by adopting a position distal to the η6‐arene ring. This preference provides a means for the prediction of the sense of asymmetric reduction. The sulfone group also facilitates the formation of a range of reduction substrates, and its
Tandem Acid/Pd‐Catalyzed Reductive Rearrangement of Glycol Derivatives
作者:Tanno A. Schmidt、Benjamin Ciszek、Prasad Kathe、Ivana Fleischer
DOI:10.1002/chem.202000251
日期:2020.3.18
investigations show that the substrate undergoes rearrangement to an aldehyde under [1,2]-H-migration and cleavage of an oxygen-based leaving group. The leaving group is trapped as its formic ester, and the aldehyde is reduced and subsequently esterified to a formate. While the rearrangement to the aldehyde is catalyzed by sulfonic acids, the reduction step requires a unique catalyst system comprising
Stereoselectivity of Baker's Yeast Reduction of 2-Propanones: Influence of Substituents.
作者:Viggo Waagen、Vassilia Partali、Ingjerd Hollingsæter、Man Shun Soon Huang、Thorleif Anthonsen、Hari N. Pati、Kirpal S. Bisht、Virinder S. Parmar、George W. Francis
DOI:10.3891/acta.chem.scand.48-0506
日期:——
The stereoselectivity of Baker'syeastreduction of prochiral alpha-oxygenated 2-propanones has been studied by varying the substrate structure. The 1-hydroxy-3-methoxy-3-propanone 1a was reduced to the corresponding alcohol (R)-2a with 88% enantiomeric excess. Replacing the hydroxy group in 1a with phenoxy or benzyloxy (1b and 1c) gave the alcohols (S)-2b and (S)-2c with 53 and 32% ee, respectively
Ring-Opening Reactions of Epoxides Catalyzed by Molybdenum(VI) Dichloride Dioxide
作者:Dillip Chand、Kandasamy Jeyakumar
DOI:10.1055/s-2008-1032163
日期:2008.3
alcohols, acetonides, and α-alkoxy ketones is achieved by using molybdenum(VI) dichloride dioxide (MoO 2 Cl 2 ) as a catalyst. Alcohol, aldehyde, oxime, tosyl, and TERT-butyldimethylsilyl functional groups are tolerated during the methanolysis and acetonidation of the functionalized epoxides. No polymerization product is observed with any of the epoxides. Direct conversion of epoxides devoid of sensitive