- Enantioselective Nickel-Catalyzed Alkyne-Azide Cycloaddition by Dynamic Kinetic Resolution
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The triazole heterocycle has been widely adopted as an isostere for the amide bond. Many native amides are α-chiral, being derived from amino acids. This makes α-N-chiral triazoles attractive building blocks. This report describes the first enantioselective triazole synthesis that proceeds via nickel-catalyzed alkyne-azide cycloaddition (NiAAC). This dynamic kinetic resolution is enabled by a spontaneous [3,3]-sigmatropic rearrangement of the allylic azide. The 1,4,5-trisubstituted triazole products, derived from internal alkynes, are complementary to those commonly obtained by the related CuAAC reaction. Initial mechanistic experiments indicate that the NiAAC reaction proceeds through a monometallic Ni complex, which is distinct from the CuAAC manifold.
- Liu, En-Chih,Topczewski, Joseph J.
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supporting information
p. 5308 - 5313
(2021/05/04)
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- Catalyst-Free Insertion of Sulfoxonium Ylides into Aryl Thiols. A Direct Preparation of β-Keto Thioethers
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Insertion of sulfoxonium ylides into the S-H bond of aryl thiols without the need for a catalyst is demonstrated, furnishing β-keto thioethers in excellent yield in most cases. The method overcomes traditional syntheses that employ metal catalysts in combination with diazo compounds or toxic and hard-prepared haloketones. The experimental setup consists of mixing the reagents in acetonitrile at room temperature. Additional experimental as well as kinetic isotopic effect studies give some insight into the mechanism of this reaction.
- Dias, Rafael M. P.,Burtoloso, Antonio C. B.
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p. 3034 - 3037
(2016/07/06)
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- A convenient and efficient α-sulfenylation of carbonyl compounds
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A method for the α-sulfenylation of carbonyl compounds by 5,5-dimethyl-2-thioxo-1,3,2-dioxaphosphorinanane-2-disulfanyl derivatives has been developed. Readily available reagents, mild reaction conditions, and excellent yields with high selectivity make t
- Okragla, Emilia,Demkowicz, Sebastian,Rachon, Janusz,Witt, Dariusz
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experimental part
p. 1720 - 1724
(2009/12/09)
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- The effects of C-S and C-Se bonds on torquoselectivity: stereoselective olefination of α-thio and α-selenoketones with ynolates
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Highly Z-selective olefination of acyclic α-thio and α-selenoketones with ynolates has been achieved, and the theoretical calculations of the transition states in the ring-opening of the intermediates, the β-lactone enolates, revealed that the torquoselectivity was controlled by the secondary orbital interactions between the σ orbital of the C-S bond or a lone pair orbital on the S and σ* orbitals of the breaking C-O bond, and the σ orbital of the breaking C-O bond or a lone pair orbital on the O on the ring and the σ* orbitals of the C-S bond. The synthetic applications of the resulting olefins are also shown.
- Yoshikawa, Takashi,Mori, Seiji,Shindo, Mitsuru
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experimental part
p. 8832 - 8838
(2010/04/06)
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- Ultrasound-promoted deoxygenation of sulphoxides by samarium - NH4Cl
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Several aromatic and aliphatic sulphoxides are selectively deoxygenated to the corresponding thioethers in high to quantitative yields by samarium metal in methanolic ammonium chloride under sonication. Other functional groups such as halides, esters, ethers, nitriles, olefins and ketones are unaffected under the present reaction conditions.
- Yadav,Subba Reddy,Srinivas,Srihari
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p. 854 - 856
(2007/10/03)
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- Indium-mediated Reaction in Aqueous Media. Synthesis of Phenacyl Sulfides by Reactions of α-Bromoketones with Sodium Alkyl Thiosulfates
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Phenacyl Sulfides are synthesized in moderate to good yields via reaction of α-haloketones with sodium alkyl thiosulfates promoted by indium metal in aqueous media.
- Zhan, Zhuangping,Zhang, Yongmin,Ma, Zhenghai
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p. 130 - 131
(2007/10/03)
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