24165-65-9Relevant academic research and scientific papers
Organocatalytic Asymmetric Synthesis of Cyclic Acetals with Spirooxindole Skeleton
Shikari, Amit,Mandal, Koushik,Chopra, Deepak,Pan, Subhas Chandra
supporting information, p. 58 - 63 (2021/11/09)
An organocatalytic asymmetric synthesis of cyclic acetal with spirooxindole skeleton has been developed via a domino reaction between isatin and γ-hydroxy enones. Bifunctional squaramide catalyst with adamantyl motif was found to be the most effective for the cascade reaction. With 10 mol% of the catalyst, the desired products were obtained in 1.8:1 to 9:1 diastereo- and 86% to >99% enantioselectivities from a range of substituted isatins and γ-hydroxy enones. (Figure presented.).
Catalytic Photoredox Allylation of Aldehydes Promoted by a Cobalt Complex
Gualandi, Andrea,Rodeghiero, Giacomo,Perciaccante, Rossana,Jansen, Thomas Paul,Moreno-Cabrerizo, Cristina,Foucher, Charles,Marchini, Marianna,Ceroni, Paola,Cozzi, Pier Giorgio
supporting information, p. 1105 - 1111 (2021/01/04)
The preparation of homoallylic alcohols by addition of organometallic allyl compounds to carbonyls is an important strategy in organic chemistry. Allylating organometallic cobalt species can be generated employing stoichiometric quantities of Zn acting as reductant. To avoid the employment of stoichiometric amount of Zn, we have developed an allylation reaction of aromatic and aliphatic aldehydes promoted by photoredox catalysis in the presence of a cobalt complex, and we present herein a full account of our research. In the presence of the abundant CoBr2 (10 mol %), 4,4′-di-tert-butyl-2,2′-dipyridyl (dtbbpy, 10 mol %), allyl acetate (3 equiv.), [Ir(dtbbpy)(ppy)2]PF6 (ppy=2-phenylpyridine, 2 mol %), and N,N-diisopropylethylamine (4 equiv.), an allylation of aldehydes is taking place, in moderate to good yields. Substrates scope, limitations, and photophysical investigations of this new process are reported. (Figure presented.).
Photoredox Allylation Reactions Mediated by Bismuth in Aqueous Conditions
Potenti, Simone,Gualandi, Andrea,Puggioli, Alessio,Fermi, Andrea,Bergamini, Giacomo,Cozzi, Pier Giorgio
supporting information, p. 1624 - 1627 (2021/02/05)
Organometallic allylic reagents are widely used in the construction of C?C bonds by Barbier-type reactions. In this communication, we have described a photoredox Barbier allylation of aldehydes mediated by bismuth, in absence of other metals as co-reductants. Mild reaction conditions, tolerance of oxygen, and use of aqueous solvent make this photoredox methodology attractive for green and sustainable synthesis of homoallylic alcohols.
Electrochemical Chalcogenation of β,γ-Unsaturated Amides and Oximes to Corresponding Oxazolines and Isoxazolines
Baidya, Mrinmay,De Sarkar, Suman,Mahanty, Kingshuk,Maiti, Debabrata,Mallick, Samrat
supporting information, (2020/02/04)
The current report represents a transition-metal-free synthesis of oxazoline and isoxazoline derivatives by a tandem electro-oxidative chalcogenation-cyclization process. Both C?Se and C?S bond-forming protocols were developed without using any external oxidant and the reaction was performed at room temperature, open to the air. Using this methodology, 29 substituted oxazoline and 16 substituted isoxazoline derivatives were synthesized with up to 91% isolated yield. (Figure presented.).
Nickel-Catalyzed Hydroarylation of in Situ Generated 1,3-Dienes with Arylboronic Acids Using a Secondary Homoallyl Carbonate as a Surrogate for the 1,3-Diene and Hydride Source
Hamaguchi, Takashi,Kawatsura, Motoi,Takahashi, Yoshiyuki,Tsuji, Hiroaki
supporting information, (2020/02/15)
The nickel-catalyzed hydroarylation of 1,3-dienes with arylboronic acids using a secondary homoallyl carbonate as a surrogate for the 1,3-diene and hydride source has been developed. The synthetic strategy allowed an efficient access to a wide array of hydroarylation products in high yields with high functional group compatibility without the use of an external hydride source. Mechanistic experiments indicated that the alkene-directed oxidative addition and subsequent β-hydride elimination would be a critical process in this transformation.
Copper-Catalyzed Aerobic Cyclization of β,γ-Unsaturated Hydrazones with Concomitant CC Bond Cleavage
Fan, Zhenwei,Feng, Jiahao,Hou, Yuchen,Rao, Min,Cheng, Jiajia
supporting information, p. 7981 - 7985 (2020/11/02)
A Cu-catalyzed aerobic oxidative cyclization of β,γ-unsaturated hydrazones for the preparation of pyrazole derivatives has been developed. The hydrazonyl radical promoted the cyclization, along with a concomitant CC bond cleavage of β,γ-unsaturated hydrazones. This process has been verified via several control experiments, including a radical-trapping study, an 18O-labeling method, and the identification of the possible byproducts. The advantages of this reaction include operational simplicity, a broad reaction scope, and a mild selective reaction process.
MnO2as a terminal oxidant in Wacker oxidation of homoallyl alcohols and terminal olefins
Fernandes, Rodney A.,Ramakrishna, Gujjula V.,Bethi, Venkati
, p. 6115 - 6125 (2020/10/27)
Efficient and mild reaction conditions for Wacker-type oxidation of terminal olefins of less explored homoallyl alcohols to β-hydroxy-methyl ketones have been developed by using a Pd(ii) catalyst and MnO2 as a co-oxidant. The method involves mild reaction conditions and shows good functional group compatibility along with high regio- and chemoselectivity. While our earlier system of PdCl2/CrO3/HCl produced α,β-unsaturated ketones from homoallyl alcohols, the present method provided orthogonally the β-hydroxy-methyl ketones. No overoxidation or elimination of benzylic and/or β-hydroxy groups was observed. The method could be extended to the oxidation of simple terminal olefins as well, to methyl ketones, displaying its versatility. An application to the regioselective synthesis of gingerol is demonstrated.
Heterocyclization involving benzylic C(sp3)-H functionalization enabled by visible light photoredox catalysis
Pandey, Ganesh,Laha, Ramkrishna,Mondal, Pradip Kumar
, p. 9689 - 9692 (2019/08/15)
A general and efficient method for heterocyclization involving benzylic C(sp3)-H functionalization enabled by visible light photoredox catalysis to access a wide range of structurally diverse oxygen as well as nitrogen heterocycles up to a gram scale is reported. The potential application of this new methodology is demonstrated by the total synthesis of (-)-codonopsinine and (+)-centrolobine. Herein it is proposed that selectfluor, unlike a fluorinating reagent, acts as an oxidative quencher and a hydrogen radical acceptor.
Stereoselective Barbier-Type Allylations and Propargylations Mediated by CpTiCl3
López-Martínez, Josefa L.,Torres-García, Irene,Rodríguez-García, Ignacio,Mu?oz-Dorado, Manuel,álvarez-Corral, Miriam
, p. 806 - 816 (2019/01/24)
CpTiCl2, prepared in situ by manganese reduction of CpTiCl3, is an excellent new system for the Barbier-type allylation and propargylation of carbonyl compounds. It can be used in catalytic amounts when combined with Et3N·HBr/TMSBr, which acts as a regenerating system. The high regio- and stereoselectivity shown by this system makes it useful for prenylation and crotylation processes in the synthesis of natural products.
[bmim][Br] as an Inexpensive and Efficient Medium for the Barbier-Type Allylation Reaction Using a Catalytic Amount of Indium: Mechanistic Studies
Dey, Papiya,Koli, Mrunesh,Goswami, Dibakar,Sharma, Anubha,Chattopadhyay, Subrata
, p. 1333 - 1341 (2018/04/02)
Barbier-type allylation reactions of aldehydes and ketones have been carried out with both unsubstituted and γ-substituted allyl bromides using only a catalytic amount (0.1 equiv.) of In metal in [bmim][Br], but not in H2O, organic solvents, or
