4079-52-1Relevant academic research and scientific papers
Intermolecular C-O Bond Formation with Alkoxyl Radicals: Photoredox-Catalyzed α-Alkoxylation of Carbonyl Compounds
Banoun, Camille,Bourdreux, Flavien,Magnier, Emmanuel,Dagousset, Guillaume
supporting information, p. 8926 - 8930 (2021/11/17)
Due to the high reactivity of alkoxyl (RO·) radicals and their propensity to easily undergo β-scission or Hydrogen Atom Transfer (HAT) reactions, intermolecular alkoxylations involving RO· radicals are barely described. We report herein for the first time the efficient intermolecular trapping of alkoxyl radicals by silyl enol ethers. This photoredox-mediated protocol enables the introduction of both structurally simple and more complex alkoxy groups into a wide range of ketones and amides.
Cobalt-Catalyzed Reductive C-O Bond Cleavage of Lignin β-O-4 Ketone Models via in Situ Generation of the Cobalt-Boryl Species
Gao, Kecheng,Xu, Man,Cai, Cheng,Ding, Yanghao,Chen, Jianhui,Liu, Bosheng,Xia, Yuanzhi
supporting information, p. 6055 - 6060 (2020/08/12)
An efficient and mild method for reductive C-O bond cleavage of lignin β-O-4 ketone models was developed to afford the corresponding ketones and phenols with PDI-CoCl2 as the precatalyst and diboron reagent as the reductant. The synthetic utility of the methodology was demonstrated by depolymerization of a polymeric model and gram-scale transformation. Mechanistic studies suggested that this transformation involves steps of carbonyl insertion, 1,2-Brook type rearrangement, β-oxygen elimination, and rate-limiting regeneration of the catalytic active Co-B species.
Transfer-dehydrogenation of secondary alcohols catalyzed by manganese NNN-pincer complexes
Budweg, Svenja,Junge, Kathrin,Beller, Matthias
supporting information, p. 14143 - 14146 (2019/12/02)
Novel catalytic systems based on pentacarbonylmanganese bromide and stable NNN-pincer ligands are presented for the transfer-dehydrogenation of secondary alcohols to give the corresponding ketones in good to excellent isolated yields. Best results are obtained using di-picolylamine derivatives as ligands and acetone as an inexpensive hydrogen acceptor. Besides high activity for benzylic substrates, aliphatic alcohols, as well as steroid derivatives, are readily oxidized in the presence of the optimal phosphorus-free catalyst.
Aerobic Photooxidative Synthesis of β-Alkoxy Monohydroperoxides Using an Organo Photoredox Catalyst Controlled by a Base
Asano, Yuya,Nagasawa, Yoshitomo,Yamaguchi, Eiji,Itoh, Akichika
, p. 409 - 412 (2018/02/21)
Transition-metal-free synthesis of β-alkoxy monohydroperoxides via aerobic photooxidation using an acridinium photocatalyst was developed. This method enables the synthesis of some novel hydroperoxides. The peroxide source is molecular oxygen, which is cost-effective and atomically efficient. Magnesium oxide plays an important role as a base in the catalytic system.
Silica-supported HClO4 promotes catalytic solvent- and metal-free O-H insertion reactions with diazo compounds
Gallo, Rafael Douglas C.,Burtoloso, Antonio C. B.
, p. 4547 - 4556 (2018/10/17)
Solvent-free O-H insertion reactions in the presence of diazo carbonyl compounds were carried-out in very mild conditions. Unlike the traditional metal-catalysed version, employing rhodium acetate dimer, this method uses eco-friendly silica-supported HClO4 as the catalyst. Only 0.3 mol% of this Br?nsted acid catalyst, that can also be recycled several times, is necessary to guarantee very good yields (up to 97%) in the O-H insertion reactions. Reaction set-up is simple and permitted the preparation of forty-three α-hydroxy and α-alkoxy esters/ketones in just 1 h and at room temperature.
Oxidation of Vicinal Diols to α-Hydroxy Ketones with H2O2 and a Simple Manganese Catalyst
Mecozzi, Francesco,Dong, Jia Jia,Saisaha, Pattama,Browne, Wesley R.
supporting information, p. 6919 - 6925 (2017/12/26)
α-Hydroxy ketones are valuable synthons in organic chemistry. Here we show that oxidation of vic-diols to α-hydroxy ketones with H2O2 can be achieved with an in situ prepared catalyst based on manganese salts and pyridine-2-carboxylic acid. Furthermore the same catalyst is effective in alkene epoxidation, and it is shown that alkene oxidation with the MnII catalyst and H2O2 followed by Lewis acid ring opening of the epoxide and subsequent oxidation of the alkene to α-hydroxy ketones can be achieved under mild (ambient) conditions.
Cross-Linked Artificial Enzyme Crystals as Heterogeneous Catalysts for Oxidation Reactions
Lopez, Sarah,Rondot, Laurianne,Leprêtre, Chloé,Marchi-Delapierre, Caroline,Ménage, Stéphane,Cavazza, Christine
supporting information, p. 17994 - 18002 (2017/12/26)
Designing systems that merge the advantages of heterogeneous catalysis, enzymology, and molecular catalysis represents the next major goal for sustainable chemistry. Cross-linked enzyme crystals display most of these essential assets (well-designed mesoporous support, protein selectivity, and molecular recognition of substrates). Nevertheless, a lack of reaction diversity, particularly in the field of oxidation, remains a constraint for their increased use in the field. Here, thanks to the design of cross-linked artificial nonheme iron oxygenase crystals, we filled this gap by developing biobased heterogeneous catalysts capable of oxidizing carbon-carbon double bonds. First, reductive O2 activation induces selective oxidative cleavage, revealing the indestructible character of the solid catalyst (at least 30 000 turnover numbers without any loss of activity). Second, the use of 2-electron oxidants allows selective and high-efficiency hydroxychlorination with thousands of turnover numbers. This new technology by far outperforms catalysis using the inorganic complexes alone, or even the artificial enzymes in solution. The combination of easy catalyst synthesis, the improvement of "omic" technologies, and automation of protein crystallization makes this strategy a real opportunity for the future of (bio)catalysis.
I 2 /TBHP-Promoted Approach to α-Keto Esters from Trifluoromethyl β-Diketones and Alcohols via C-C Bond Cleavage
Shao, Tongle,Fang, Xiang,Zhou, Jun,Jin, Chen,Yang, Xueyan,Wu, Fanhong
, p. 2018 - 2023 (2017/09/13)
A metal-free oxidative coupling reaction of trifluoromethyl β-diketones with alcohols for the synthesis of α-keto esters in good to excellent yields has been developed. Preliminary mechanistic studies suggest that an I 2 /TBHP promoted sequential iodination, C-C bond cleavage, C-O bond formation and oxidation pathway is involved in this reaction.
Additions of Organomagnesium Halides to α-Alkoxy Ketones: Revision of the Chelation-Control Model
Read, Jacquelyne A.,Yang, Yingying,Woerpel
supporting information, p. 3346 - 3349 (2017/07/13)
The chelation-control model explains the high diastereoselectivity obtained in additions of organometallic nucleophiles to α-alkoxy ketones but fails for reactions of allylmagnesium halides. Low diastereoselectivity in ethereal solvents results from no chelation-induced rate acceleration. Additions of allylmagnesium bromide to carbonyl compounds are diastereoselective using CH2Cl2 as the solvent even though rate acceleration is still absent. Stereoselectivity likely arises from the predominance of the chelated form in solution. Therefore, a revised chelation-control model is proposed.
Direct Synthesis of α-Alkoxy Ketones by Oxidative C–O Bond Formation
Yu, Hui,Xu, Yilan,Fang, Yan,Dong, Rui
, p. 5257 - 5262 (2016/11/13)
A 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.
