13522-65-1Relevant articles and documents
Electrochemically Catalyzed Newman-Kwart Rearrangement: Mechanism, Structure-Reactivity Relationship, and Parallels to Photoredox Catalysis
Roesel, Arend F.,Ugandi, Mihkel,Huyen, Nguyen Thi Thu,Májek, Michal,Broese, Timo,Roemelt, Michael,Francke, Robert
, p. 8029 - 8044 (2020/07/25)
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.
Ambient-Temperature Newman-Kwart Rearrangement Mediated by Organic Photoredox Catalysis
Perkowski, Andrew J.,Cruz, Cole L.,Nicewicz, David A.
supporting information, p. 15684 - 15687 (2016/01/09)
The Newman-Kwart rearrangement is perhaps the quintessential method for the synthesis of thiophenols from the corresponding phenol. However, the high thermal conditions required for the rearrangement of the requisite O-aryl carbamothioates often leads to decomposition. Herein, we present a general strategy for catalysis of O-aryl carbamothioates to S-aryl carbamothioates using catalytic quantities of a commercially available organic single-electron photooxidant. Importantly, this reaction is facilitated at ambient temperatures.
Thiocarbamates and their derivatives
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, (2008/06/13)
A process is provided for preparing N-acyl-aminothiophenols, e.g., N-acetyl-para-aminothiophenol, or aminothiophenols, e.g., para-aminothiophenol, by reacting a hydroxy aromatic ketone, e.g., 4-hydroxyacetophenone (4-HAP), with hydroxylamine or a hydroxylamine salt, to form the oxime of the ketone, subjecting the oxime to a Beckmann rearrangement in the presence of a catalyst to form the N-acyl-hydroxy aromatic amine, e.g., N-acetyl-para-aminophenol (APAP), reacting the N-acyl-hydroxy aromatic amine with an N,N-di (organo) thiocarbamoyl halide, e.g., N,N-dimethylthiocarbamoyl chloride, to form an O-(N-acyl-aminoaryl)-N,N-di (organo) thiocarbamate, e.g., O-(N-acetyl-para-aminophenyl)-N,N-dimethylthiocarbamate, pyrolytically rearranging the O-(N-acyl-aminoaryl)-N,N-di (organo) thiocarbamate to form an S-(N-acyl-aminoaryl)-N,N-di (organo) thiocarbamate, e.g., S-(N-acetyl-para-aminophenyl)-N,N-dimethylthiocarbamate, and hydrolyzing the latter compound to obtain the N-acyl aminothiophenol or aminothiophenol. The N-acyl aminothiophenol may be reacted with an acylating agent to form the N,S-diacyl-aminothiophenol, e.g., N,S-diacetyl-p-aminothiophenol, or may be further hydrolyzed to the aminothiophenol, e.g., p-aminothiophenol.
