6270-34-4Relevant academic research and scientific papers
The first synthesis of cyclopropanone acetals from the reaction of Fischer carbene complexes with ketene acetals
Wang, Siu Ling B.,Goldberg, Daniel R.,Liu, Xuejun,Su, Jing,Zheng, Qi-Huang,Liptak, Vincent,Wulff, William D.
, p. 6101 - 6110 (2005)
The reaction of iso-propoxy stabilized Fischer carbene complexes with ketene acetals gives moderate to excellent yields of cyclopropanone acetals when carried out under a carbon monoxide atmosphere. This is in contrast to the known reaction of methoxy substituted complexes which give cyclic ortho esters under the same conditions. A mechanism is proposed which involves a branch point between the two products as the zwitterionic intermediate resulting from nucleophilic addition of the ketene acetal to the carbene carbon. A 1,3-migration of the methoxyl group to the cationic center leads to the ortho ester and a ring closure by backside attack leads to the cyclopropanone acetal. A double-labeling experiment shows that the 1,3-migration occurs by an intramolecular process that is proposed to involve a bridging oxonium ion. The effect of the isopropoxy group is thus interpreted to be to sterically hinder the formation of a bridged oxonium ion.
Study of the oxidative esterification of furfural catalyzed by Au25(glutathione)18 nanocluster deposited on zirconia
Shahin, Zahraa,Rataboul, Franck,Demessence, Aude
, (2020/11/24)
Au/ZrO2 catalyst prepared from Au25(SG)18 nanoclusters (SG stands for glutathione) deposited on ZrO2 has shown to be an efficient system for the oxidative esterification of furfural with methanol. The influence of the supported nanoclusters was studied and showed that partial calcination of the supported nanoclusters at 300 °C was sufficient for a quantitative formation of methyl-2-furoate even in the absence of a base. In the presence of 0.27 mol% of Au, initial activities up to 250 h?1 were obtained at 100 °C under 6 bar of O2. The reactivity was extended to the oxidative esterification of furfuryl alcohol and the formation of various products and intermediates was discussed.
Synthesis of [2,2’]Bifuranyl-5,5’-dicarboxylic Acid Esters via Reductive Homocoupling of 5-Bromofuran-2-carboxylates Using Alcohols as Reductants?
Jiang, Huanfeng,Luo, Jiajun,Xie, Yi,Yin, Biaolin,Yu, Bin
, p. 62 - 68 (2020/12/09)
Herein, we describe an environmentally benign and cost-effective protocol for the synthesis of valuable bifuranyl dicarboxylates, starting with α-bromination of readily accessible furan-2-carboxylates by LiBr and K2S2O8. Furthermore, the bromination intermediate product 5-bromofuran-2-carboxylates were then conducted in a palladium-catalyzed reductive homocoupling reactions in the presence of alcohols to afford bifuranyl dicarboxylates. One of the final products in this protocol, [2,2’]bifuran-5,5’-dicarboxylic acid esters, are essential monomers of poly(ethylene bifuranoate), which can be served as an green and versatile alternative polymer for traditional poly(ethylene terephthalate) that is currently common in technical plastics.
Direct Alkoxycarbonylation of Heteroarenes via Cu-Mediated Trichloromethylation and in Situ Alcoholysis
Jiang, Huanfeng,Jiang, Kai,Li, Yingwei,Luo, Wenkun,Yin, Biaolin
supporting information, (2020/03/04)
We report an efficient approach for direct alkoxycarbonylation of furans as well as other heteroarenes via a one-step copper-mediated reaction of three components (i.e., heteroarene, alcohol, and CHCl3). The copper additive was confirmed to simultaneously promote the reaction in three pathways: oxidant cracking, single electron transfer, and alcoholysis. By means of this protocol, various functionalized furancarboxylates and other heteroarenecarboxylates were facilely obtained in moderate to good yields.
In situ MnOx/N-doped carbon aerogels from cellulose as monolithic and highly efficient catalysts for the upgrading of bioderived aldehydes
Zhou, Shenghui,Chen, Guixian,Feng, Xiao,Wang, Ming,Song, Tao,Liu, Detao,Lu, Fachuang,Qi, Haisong
, p. 3593 - 3603 (2018/08/17)
Herein, we report a sustainable route to in situ synthesize a monolithic MnOx/N-doped carbon aerogel catalyst (Mn-NCA) by pyrolysing MnO(OH)2-cellulose aerogel precursors based on an alkali-urea aqueous system. The as-obtained Mn-NCA showed highly efficient catalytic activity for the transfer hydrogenation of a broad range of biomass-derived aldehydes, yielding 90-100% conversion and 64-100% selectivity to the corresponding alcohols under mild conditions in an oven without agitation. A combination of controlled experiments and detailed characterization studies indicated that the superior performance of Mn-NCA is attributed to the monolithic three-dimensional (3D) hierarchical porous architecture and the synergistic effects between homogeneously dispersed MnOx nanoparticles (NPs) and urea-derived basic sites. The monolithic feature of Mn-NCA exhibits superior dispersibility and separability compared to conventional centrifugation and filtration techniques in a powdery catalytic system. Moreover, a possible reaction mechanism is proposed. Our work provides a new method for developing highly efficient monolithic catalysts from renewable biopolymers for biomass valorization.
GAS-PHASE PYROLYTIC REACTIONS. PART 4. ARRHENIUS PARAMETERS AND HAMMETT ρ CONSTANTS IN GAS-PHASE ELIMINATIONS OF ALKYL PYRIDYL-, FURYL-, AND THIENYLCARBOXYLATE ESTERS
Al-Awadi, Nouria A.,Al-Bashir, Rasha F.,ElDusouqui, Osman M. E.
, p. 2911 - 2916 (2007/10/02)
The first-order rate coefficients ( 105k/s-1) of the gas-phase pyrolytic reactions of seven isopropyl (hetero)arylcarboxylate esters were calculated for 600 K to be: 75.34 for benzoate, and 100.0, 70.46, 94.03, 65.58, 100.9 and 120.2 for 2-thienyl-, 3-thienyl-, 2-furyl-, 3-furyl-, 3-pyridyl- and 4-pyridylcarboxylate, respectively.The corresponding Hammett replacement ρ0 substituent constants of the heterocyclic groups are: 0.53, -0.13, 0.42, -0.26, 0.55 and 0.88, respectively.The reported ρ0 constants are in agreement with other gas-phase and solution data, and are amenable to rationalization in terms of normal electronic and structural effects.Further, the physical constants of four new isopropyl heteroarylcarboxylate esters are described.
OXIDATIVE BENZOIN REACTIONS
Castells, J.,Pujol, F.,Llitjos, H.,Moreno-Manas, M.
, p. 337 - 346 (2007/10/02)
A one-pot synthesis (yields over 50percent) of methyl and ethyl esters from aldehydes (and the corresponding alcohol), using aromatic nitrocompounds as oxidizing agents under the catalytic action of cyanide ion or of a conjugate base of a thiazolium ion, is described.A variety of by-products (α-hydroxybenzylidenaniline (16), α-methoxybenzylidenaniline (21), α-cyanobenzylidenaniline (27), N1-hydroxy-N1,N2-diphenylbenzamidine (28), and others) have been identified.
