4423-94-3Relevant articles and documents
The Use of On-line H/D Exchange for the Investigation of Alcohols and Carbonyl Compounds by Reaction Gas Chromatography/Mass Spectrometry
Mikaya, A. I.,Zaikin, V. G.,Antonova, A. V.,Prostakov, N. S.
, p. 521 - 522 (1984)
-
Chihara,Tanaka
, p. 512,513 (1979)
Deciphering Reactivity and Selectivity Patterns in Aliphatic C-H Bond Oxygenation of Cyclopentane and Cyclohexane Derivatives
Martin, Teo,Galeotti, Marco,Salamone, Michela,Liu, Fengjiao,Yu, Yanmin,Duan, Meng,Houk,Bietti, Massimo
supporting information, p. 9925 - 9937 (2021/06/30)
A kinetic, product, and computational study on the reactions of the cumyloxyl radical with monosubstituted cyclopentanes and cyclohexanes has been carried out. HAT rates, site-selectivities for C-H bond oxidation, and DFT computations provide quantitative information and theoretical models to explain the observed patterns. Cyclopentanes functionalize predominantly at C-1, and tertiary C-H bond activation barriers decrease on going from methyl- and tert-butylcyclopentane to phenylcyclopentane, in line with the computed C-H BDEs. With cyclohexanes, the relative importance of HAT from C-1 decreases on going from methyl- and phenylcyclohexane to ethyl-, isopropyl-, and tert-butylcyclohexane. Deactivation is also observed at C-2 with site-selectivity that progressively shifts to C-3 and C-4 with increasing substituent steric bulk. The site-selectivities observed in the corresponding oxidations promoted by ethyl(trifluoromethyl)dioxirane support this mechanistic picture. Comparison of these results with those obtained previously for C-H bond azidation and functionalizations promoted by the PINO radical of phenyl and tert-butylcyclohexane, together with new calculations, provides a mechanistic framework for understanding C-H bond functionalization of cycloalkanes. The nature of the HAT reagent, C-H bond strengths, and torsional effects are important determinants of site-selectivity, with the latter effects that play a major role in the reactions of oxygen-centered HAT reagents with monosubstituted cyclohexanes.
Enantioselective Protonation of Enol Esters with Bifunctional Phosphonium/Thiourea Catalysts
Yamamoto, Eiji,Wakafuji, Kodai,Mori, Yusuke,Teshima, Gaku,Hidani, Yuki,Tokunaga, Makoto
supporting information, p. 4030 - 4034 (2019/06/07)
Bifunctional phosphonium/thioureas derived from tert-leucine behaved as highly selective catalysts for enantioselective protonation of enol esters, providing α-chiral ketones in yields of up to 99% with high enantioselectivities (up to 98.5:1.5 er). Control experiments clarified that a bulky tert-butyl group and phosphonium and thiourea moieties were necessary to achieve such high stereoselectivity. In addition, mechanistic investigations indicated the catalyst was converted to the corresponding betaine species, which served as a monomolecular catalyst.
Regioselective ketone α-alkylation with simple olefins via dual activation
Mo, Fanyang,Dong, Guangbin
, p. 68 - 72 (2014/07/21)
Alkylation of carbonyl compounds is a commonly used carbon-carbon bond-forming reaction. However, the conventional enolate alkylation approach remains problematic due to lack of regioselectivity, risk of overalkylation, and the need for strongly basic conditions and expensive alkyl halide reagents. Here, we describe development of a ketone-alkylation strategy using simple olefins as the alkylating agents. This strategy employs a bifunctional catalyst comprising a secondary amine and a low-valent rhodium complex capable of activating ketones and olefins simultaneously. Both cyclic and acyclic ketones can be mono-a-alkylated with simple terminal olefins, such as ethylene, propylene, 1-hexene, and styrene, selectively at the less hindered site; a large number of functional groups are tolerated.The pH/redox neutral and byproduct-free nature of this dual-activation approach shows promise for large-scale syntheses.
