The reaction of PhCOCH2Br and NaOMe in MeOH gave PhCOCH2OH as the major product and PhCOCH2OMe as the minor product. Substituent effects on the reactivity and product selectivity revealed that an electron-withdrawing substituent on the phenyl ring enhanced the overall reactivity and gave more alcohol than ether. It was indicated that the alcohol was formed via carbonyl addition-epoxidation, whereas the ether was formed by direct substitution. Substituent effects on the reaction rates, as well as the effects of NaOMe concentration on the rate and product ratio for both reactions of PhCOCH2Br and PhCOCH2Cl are in line with the mechanism that the alcohol and ether products were formed via two independent and concurrent routes, carbonyl addition and α-carbon attack, respectively, and thus the reaction mechanism could be different from the bifurcation mechanism previously predicted for the reaction of PhCOCH2Br by a simulation study in the gas phase.
The continuous flow reaction of various aryl or heteroaryl bromides in toluene in the presence of THF (1.0 equiv) with sec-BuLi (1.1 equiv) provided at 25 °C within 40 sec the corresponding aryllithiums which were acylated with various functionalized N,N-dimethylamides including easily enolizable amides at −20 °C within 27 sec, producing highly functionalized ketones in 48–90 % yield (36 examples)
Catalytic [3+3] Annulation of
<scp>β‐Ketoethers</scp>
and Cyclopropenones
<i>via</i>
C(sp
<sup>3</sup>
)—O/C—C Bond Cleavage under
<scp>Transition‐Metal</scp>
Free Conditions
carbon-oxygen (C—O) bond is highly important for the transformation of oxygen-rich biomass and industry chemicals. Herein, an efficient [3+3] annulation of β-ketoethers with cyclopropenones in the presence of catalytic base has been developed, which proceeds through the C(sp3)—O bonds cleavage in β-ketoethers and C—C bond cleavage in cyclopropenones under transition-metal free conditions. The cleavage of C(sp3)—O
Direct Synthesis of α-Alkoxy Ketones by Oxidative C-O Bond Formation
作者:Hui Yu、Yilan Xu、Yan Fang、Rui Dong
DOI:10.1002/ejoc.201600723
日期:2016.11
convenient method to prepare α-alkoxy ketones has been developed by oxidative coupling of aryl methyl ketones and alcohols. With aqueous tert-butyl hydroperoxide (6.0 equiv.) as the oxidant, tetrabutylammonium iodide (20 mol-%) as the catalyst, and TsNHNH2 (1.0 equiv.) as the additive, ketones underwent direct alkoxylation to give α-methoxy or α-ethoxy ketones in moderate to good yields.