- Carbamates: A Directing Group for Selective C-H Amidation and Alkylation under Cp*Co(III) Catalysis
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The selective reactivity of carbamate and thiocarbamate toward alkylation and amidation is reported under stable, high-valent, cost-effective cobalt(III) catalysis. This method reveals the wide possibility of designing a different branch of synthetically
- Bera, Sourav Sekhar,Maji, Modhu Sudan
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supporting information
p. 2615 - 2620
(2020/04/08)
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- Electrochemically Catalyzed Newman-Kwart Rearrangement: Mechanism, Structure-Reactivity Relationship, and Parallels to Photoredox Catalysis
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The facilitation of redox-neutral reactions by electrochemical injection of holes and electrons, also known as "electrochemical catalysis", is a little explored approach that has the potential to expand the scope of electrosynthesis immensely. To systematically improve existing protocols and to pave the way toward new developments, a better understanding of the underlying principles is crucial. In this context, we have studied the Newman-Kwart rearrangement of O-arylthiocarbamates to the corresponding S-aryl derivatives, the key step in the synthesis of thiophenols from the corresponding phenols. This transformation is a particularly useful example because the conventional method requires temperatures up to 300 °C, whereas electrochemical catalysis facilitates the reaction at room temperature. A combined experimental-quantum chemical approach revealed several reaction channels and rendered an explanation for the relationship between the structure and reactivity. Furthermore, it is shown how rapid cyclic voltammetry measurements can serve as a tool to predict the feasibility for specific substrates. The study also revealed distinct parallels to photoredox-catalyzed reactions, in which back-electron transfer and chain propagation are competing pathways.
- Roesel, Arend F.,Ugandi, Mihkel,Huyen, Nguyen Thi Thu,Májek, Michal,Broese, Timo,Roemelt, Michael,Francke, Robert
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p. 8029 - 8044
(2020/07/25)
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- Base-Promoted Synthesis of O -Aryl/Alkyl N, N -Dimethylthiocarbamates Starting from Inexpensive and Environmentally Benign Disulfide
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A series of O -aryl (alkyl) N, N -dimethylthiocarbamates were synthesized in good yields (70-77%) by reacting substituted phenols or alkyl alcohol with inexpensive, stable, and environmentally benign tetramethylthiuram disulfide (TMTD) in the presence of NaH. By avoiding use of the toxic and corrosive N, N -dialkylthiocarbamoyl chloride, the method provides a green and facile preparation for some important precursors of potentially biologically reactive compounds.
- Dong, Zhi-Bing,Wang, Ming,Zhu, Hui,Liu, Xing,Chang, Cai-Zhu
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p. 5258 - 5262
(2017/10/06)
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- The Newman-Kwart rearrangement: A microwave kinetic study
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(Chemical Equation Presented) The kinetic profile of the Newman-Kwart rearrangement has been evaluated using microwave heating. After first demonstrating equivalence between conventional convective heating and microwave heating, data was gathered and anal
- Gilday, John P.,Lenden, Philip,Moseley, Jonathan D.,Cox, Brian G.
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p. 3130 - 3134
(2008/09/19)
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- The Newman-Kwart rearrangement re-evaluated by microwave synthesis
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The Newman-Kwart rearrangement (NKR) has been re-evaluated by microwave heating. Microwave technology has proven to be ideal for investigating this high temperature rearrangement and facilitated the confirmation of many aspects of this valuable reaction.
- Moseley, Jonathan D.,Sankey, Rosalind F.,Tang, Olivier N.,Gilday, John P.
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p. 4685 - 4689
(2007/10/03)
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- Cycloaddition in synthesis of sulfonamide derivatives. IV. One-pot synthesis of 3-dimethylamino-4,1,2-benzoxathiazine 1,1-dioxides, 3-methoxy-4-methyl-1,2,4-benzothiadiazine 1,1-dioxide and 3-dimethylamino-1,4,2-benzodithiazine 1,1-dioxides
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A novel, one-pot synthesis of 3-dimethylamino-4,1,2-benzoxathiazine 1,1-dioxides (7), 3-methoxy-4-methyl-1,2,4-benzothiadiazine 1,1-dioxide (9) and 3-dimethylamino-1,4,2-benzodithiazine 1,1-dioxides (11) is described. The procedure in the case of 7 involv
- Iwakawa,Tamura,Murabayashi,Hayase
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p. 1939 - 1943
(2007/10/02)
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- Rapid and Selective Reduction of Functionalized Aromatic Disulfides with Lithium Tri-tert-butoxyaluminohydride. A Remarkable Steric and Electronic Control. Comparison of Various Hydride Reagents
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Lithium tri-tert-butoxyaluminohydride (LTBA), an exceptionally mild reducing agent in organic synthesis, reduces functionalized aromatic disulfides to the corresponding thiols in quantitative yield.The reaction is rapid (for example, o-tolyl disulfide is reduced to completion in 60 min at 25 deg C) and can tolerate a wide variety of functional groups, such as halogen, nitro, carboxylic acid, and their derivatives.The presence of electron-withdrawing substituents dramatically enhances the rate of reduction (p-chlorophenyl disulfide is quantitatively reduced in 30 s) and electron-releasing substituents diminishes the rate of cleavage.The reaction is sensitive to steric effects (2,4-di-tert-pentylphenyl disulfide underwent 25percent reduction in 24 h).However, such hindered disulfides can be rapidly and quantitatively reduced in refluxing THF.The reaction of LTBA with alkyl disulfides is extremely sluggish.The reaction provides a useful and simple means for the facile and selective reduction of aromatic disulfides where this is required in synthetic operations.
- Krishnamurthy, S.,Aimino, D.
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p. 4458 - 4462
(2007/10/02)
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