4248-25-3Relevant academic research and scientific papers
Vinyl Azides as Radical Acceptors in the Vitamin B12-Catalyzed Synthesis of Unsymmetrical Ketones
Dworakowski, Krzysztof R.,Pisarek, Sabina,Hassan, Sidra,Gryko, Dorota
supporting information, p. 9068 - 9072 (2021/11/30)
Vinyl azides are very reactive species and as such are useful building blocks, in particular, in the synthesis of N-heterocycles. They can also serve as precursors of ketones. These form in reactions of vinyl azides with nucleophiles or radicals. We have found, however, that under light irradiation vitamin B12 catalyzes the reaction of vinyl azides with electrophiles to afford unsymmetrical carbonyl compounds in decent yields. Mechanistic studies revealed that alkyl radicals are key intermediates in this transformation.
Metal-Free, Visible-Light-Induced Selective C?C Bond Cleavage of Cycloalkanones with Molecular Oxygen
Xin, Hong,Duan, Xin-Hua,Liu, Le,Guo, Li-Na
supporting information, p. 11690 - 11694 (2020/08/21)
A metal-free, visible-light-induced oxidative C?C bond cleavage of cycloketones with molecular oxygen is described. Cooperative Br?nsted-acid catalysis and photocatalysis enabled selective C?C bond cleavage of cycloketones to generate an array of γ-, δ- and ?-keto esters under very mild conditions. Mechanistic studies indicate that singlet molecular oxygen (1O2) is responsible for this transformation.
Photoredox Reaction of 2-Mercaptothiazolinium Salts with Silyl Enol Ethers
Zemtsov, Artem A.,Ashirbaev, Salavat S.,Levin, Vitalij V.,Kokorekin, Vladimir A.,Korlyukov, Alexander A.,Dilman, Alexander D.
, (2019/11/29)
A method for the generation of free radicals from thiazolinium salts upon photocatalytic reduction is described. The thiazolinium salts are generated by treatment with methyl triflate of 2-mercaptothiazolines, which can be readily obtained from alkyl bromides and tosylates via a nucleophilic substitution reaction or by hydrothiolation of alkenes. Silyl enol ethers were used to trap the radicals, furnishing ketones after successive single-electron oxidation and elimination of the silyl cation.
Nickel-Catalyzed Coupling of Arylzinc Halides with Thioesters
Gehrtz, Paul H.,Kathe, Prasad,Fleischer, Ivana
supporting information, p. 8774 - 8778 (2018/06/26)
The Pd-catalyzed Fukuyama reaction of thioesters with organozinc reagents is a mild, functional-group-tolerant method for acylation chemistry. Its Ni-catalyzed variant might be a sustainable alternative to expensive catalytic Pd sources. We investigated the reaction of S-ethyl thioesters with aryl zinc halides with hetero- and homotopic Ni precatalysts and several ligands. The results show that both homo- and heterotopic species may contribute to catalysis. The substrate scope using an operationally homogeneous defined Ni complex was established. Acyl radicals are postulated as short-lived intermediates.
Intermolecular Photocatalyzed Heck-like Coupling of Unactivated Alkyl Bromides by a Dinuclear Gold Complex
Xie, Jin,Li, Jian,Weingand, Vanessa,Rudolph, Matthias,Hashmi, A. Stephen K.
supporting information, p. 12646 - 12650 (2016/08/30)
A practical protocol for a photocatalyzed alkyl-Heck-like reaction of unactivated alkyl bromides and different alkenes promoted by dinuclear gold photoredox catalysis in the presence of an inorganic base is reported. Primary, secondary, and tertiary unactivated alkyl bromides with β-hydrogen can be applied. Esters, aldehydes, ketones, nitriles, alcohols, heterocycles, alkynes, alkenes, ethers, and halogen moieties are all well tolerated. In addition to 1,1-diarylalkenes, silylenolethers and enamides can also be applied, which further increases the synthetic potential of the reaction. The mild reaction conditions, broad substrate scope, and an excellent functional-group tolerance deliver an ideal tool for synthetic chemists that can even be used for challenging late-stage modifications of complex natural products.
Cobalt-catalyzed intermolecular hydroacylation of olefins through chelation-assisted imidoyl C-H activation
Yang, Junfeng,Seto, Yuan Wah,Yoshikai, Naohiko
, p. 3054 - 3057 (2015/05/20)
A low-valent cobalt catalyst generated from cobalt(II) bromide, a diphosphine ligand, and zinc powder promotes intermolecular hydroacylation of olefins using N-3-picolin-2-yl aldimines as aldehyde equivalents, which affords, upon acidic hydrolysis, ketone products in moderate to good yields with high linear selectivity. The reaction is applicable to styrenes, vinylsilanes, and aliphatic olefins as well as to various aryl and heteroaryl aldimines. The cobalt catalysis features a distinctively lower reaction temperature (60 °C) compared with those required for the same type of transformations catalyzed by rhodium complexes (typically 130-150°C).
Synthesis of γ-, δ-, and ε-lactams by asymmetric transfer hydrogenation of N-(tert-butylsulfinyl)iminoesters
Guijarro, David,Pablo, Oscar,Yus, Miguel
, p. 3647 - 3654 (2013/05/22)
Highly enantiomerically enriched γ- and δ-lactams have been prepared by a simple and very efficient procedure that involves the asymmetric transfer hydrogenation of N-(tert-butylsulfinyl)iminoesters followed by desulfinylation of the nitrogen atom and spo
Et2Zn-mediated rearrangement of bromohydrins
Li, Lezhen,Cai, Peijie,Guo, Qingxiang,Xue, Song
, p. 3516 - 3522 (2008/09/20)
(Chemical Equation Presented) A simple and highly efficient method for the rearrangement of bromohydrins mediated by Et2Zn to synthesize carbonyl compounds was described. Various β-bromo alcohols were treated with 0.6 equiv of Et2Zn to form a zinc complex in CH 2Cl2 at room temperature for 2 h, followed by 1,2-migration to give the corresponding carbonyl compounds. This remarkable and clean rearrangement is general for acyclic and cyclic bromohydrins, and a variety of ring-expansive and -contractive carbonyl compounds were obtained in good to excellent yields according to the feature of the starting bromohydrins. The functional group tolerance of organozinc reagents in this reaction will be useful in organic synthesis. The scope and limitations of this rearrangement process were also investigated.
Pd(OH)2/C (Pearlman's catalyst): A highly active catalyst for Fukuyama, Sonogashira, and Suzuki coupling reactions
Mori, Yoshikazu,Seki, Masahiko
, p. 1571 - 1574 (2007/10/03)
Treatment of thiol esters 1 with zinc reagent 2 in the presence of a small amount (2/C (Pearlman's catalyst) provided functionalized asymmetrical ketones 3 in high yields. The use of Pd(OH)2/C was
