20731-93-5Relevant articles and documents
Synergistic Relay Reactions To Achieve Redox-Neutral α-Alkylations of Olefinic Alcohols with Ruthenium(II) Catalysis
Kan, Jian,Li, Chao-Jun,Li, Chen-Chen,Li, Jianbin,Lv, Leiyang,Qiu, Zihang
, p. 4544 - 4549 (2020/02/04)
Herein, we report a ruthenium-catalyzed redox-neutral α-alkylation of unsaturated alcohols based on a synergistic relay process involving olefin isomerization (chain walking) and umpolung hydrazone addition, which takes advantage of the interaction between the two rather inefficient individual reaction steps to enable an efficient overall process. This transformation shows the compatibility of hydrazone-type “carbanions” and active protons in a one-pot reaction, and at the same time achieves the first Grignard-type nucleophilic addition using olefinic alcohols as latent carbonyl groups, providing a higher yield of the corresponding secondary alcohol than the classical hydrazone addition to aldehydes does. A broad scope of unsaturated alcohols and hydrazones, including some complex structures, can be successfully employed in this reaction, which shows the versatility of this approach and its suitability as an alternative, efficient means for the generation of secondary and tertiary alcohols.
New ligands and structural insights into the catalytic asymmetric addition of organozinc reagents to ketones
Huelgas, Gabriela,Larochelle, Lynne K.,Rivas, Lucrecia,Luchinina, Yekaterina,Toscano, Rubén A.,Carroll, Patrick J.,Walsh, Patrick J.,Anaya De Parrodi, Cecilia
experimental part, p. 4467 - 4474 (2011/08/04)
The catalytic asymmetric addition of alkyl groups to ketones has received considerable attention. Outlined herein is the synthesis of two new ligands based on the C2-symmetric 11,12-diamino-9,10-dihydro-9,10- ethanoanthracene. The scope of the new ligands has been evaluated in the catalytic asymmetric addition of diethylzinc to a variety of ketones. Enantioselectivities as high as 99% have been achieved. The structures of two of these ligands have been determined by X-ray crystallography and are compared with related structures. Additionally, the structure of a titanium complex bound to a bis(sulfonamide) diol ligand is reported.
13C NMR spectroscopic comparison of sterically stabilized meta and para-substituted o-tolyldi(adamant-l-yl)methyl cations with conjugatively stabilized benzyl cations
Lomas, John S.
, p. 2601 - 2609 (2007/10/03)
A series of meta- and para-substituted anti-o-tolyldi(adamant-1-yl)methyl cations has been generated by reaction of anti-o-tolyldi(adamant-1-yl)methanols with trifluoroacetic acid in chloroform. 13C NMR spectroscopy indicates small but significant variations in the chemical shifts of the charged carbon and its nearest neighbours on the adamantyl groups, and departures from additivity of substituent effects on the shifts of the aromatic carbons. Previous work on the closely related di(adamant-1-yl)benzyl cations is discussed. Comparison with data on aryl-substituted carbocations in superacid media reveals marked differences in the aromatic carbon shifts in the two types of carbocation. The dihedral angle between aryl and carbocation planes in aryldi(adamant-1-yl)methyl cations is estimated to be about 60°.
