99357-64-9Relevant academic research and scientific papers
Coordination-Induced Stereocontrol over Carbocations: Asymmetric Reductive Deoxygenation of Racemic Tertiary Alcohols
Isomura, Mayuko,Petrone, David A.,Carreira, Erick M.
supporting information, p. 4738 - 4748 (2019/03/19)
The inherent difficulty in eliciting facial control over carbocations has limited their utility as intermediates in asymmetric catalysis. We have now shown that a docking strategy involving the reversible coordination of a substrate to a chiral transition-metal catalyst can be used to enable highly stereoselective nucleophilic attack on intermediate tertiary carbocations. This approach has been implemented to achieve the first example of enantioselective reductive deoxygenation of tertiary alcohols. This reduction occurs with high enantio- (up to 96% ee) and regioselectivity (up to >50:1 rr) by applying a novel Hantzsch ester analogue as a convenient hydride source. In-depth mechanistic studies support the involvement of a tertiary carbocation that is coordinated to the iridium metal center via the key allene moiety.
Transition-Metal-Free Radical Hydrotrifluoromethylation of Alkynes
Matcha, Kiran,Antonchick, Andrey P.
supporting information, p. 309 - 312 (2019/01/24)
A combination of readily available and bench-stable CF3SO2Na and tBuOOH was efficiently used for hydrotrifluoromethylation of alkynes. An excellent trans-selectivity was demonstrated in the synthesis of alkenes. The developed mild reaction conditions allow the supression of the competing Meyer–Schuster-type rearrangement.
An enzymatic toolbox for the kinetic resolution of 2-(Pyridin-x-yl)but-3- yn-2-ols and tertiary cyanohydrins
Nguyen, Giang-Son,Kourist, Robert,Paravidino, Monica,Hummel, Anke,Rehdorf, Jessica,Orru, Romano V. A.,Hanefeld, Ulf,Bornscheuer, Uwe T.
experimental part, p. 2753 - 2758 (2010/07/06)
The kinetic resolution of a series of acetates of tertiary alcohols bearing a nitrogen substituent has been studied by using several recombinant carboxyl esterases and variants thereof expressed in E. coli. Most of the enzymes were active in the conversion of these tertiary alcohols and excellent enantioselectivities were achieved in the synthesis of three 2-(pyridin-x-yl)but-3-yn-2-ols with the nitrogen atom in the pyridine ring in the 2′-, 3′-, and 4′-positions. The resolution of tertiary cyanohydrins proved to be more difficult as the enantioselectivity of the enzymes was generally lower. Nevertheless, (S)-1-cyano-2,2,2-trifluoro-1- phenylethyl acetate was obtained with 99% ee. The results show that the limited substrate range of the individual enzymes in the synthesis of a series of tertiary alcohols can be efficiently overcome by using a combination of different enzymes.
