- Decarboxylative Cyanation of Aliphatic Carboxylic Acids via Visible-Light Flavin Photocatalysis
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An operationally simple method is disclosed for the decarboxylative cyanation of aliphatic carboxylic acids at room temperature. Riboflavin tetraacetate, which is an inexpensive organic photocatalyst, promotes the oxidation of carboxylic acids upon visible-light activation. After decarboxylation, the generated radicals are trapped by TsCN, yielding the desired nitriles without any further additive, in a redox-neutral process. Importantly, this protocol can be adapted to flow conditions.
- Ramirez, Nieves P.,K?nig, Burkhard,Gonzalez-Gomez, Jose C.
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supporting information
(2019/03/08)
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- C(sp3)?H Cyanation Promoted by Visible-Light Photoredox/Phosphate Hybrid Catalysis
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Inspired by the reaction mechanism of photo-induced DNA cleavage in nature, a C(sp3)?H cyanation reaction promoted by visible-light photoredox/phosphate hybrid catalysis was developed. Phosphate radicals, generated by one-electron photooxidation of phosphate salt, functioned as a hydrogen-atom-transfer catalyst to produce nucleophilic carbon radicals from C(sp3)?H bonds with a high bond-dissociation energy. The resulting carbon radicals were trapped by a cyano radical source (TsCN) to produce the C?H cyanation products. Due to the high functional-group tolerance and versatility of the cyano group, the reaction will be useful for realizing streamlined building block syntheses and late-stage functionalization of drug-like molecules.
- Wakaki, Takayuki,Sakai, Kentaro,Enomoto, Takafumi,Kondo, Mio,Masaoka, Shigeyuki,Oisaki, Kounosuke,Kanai, Motomu
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p. 8051 - 8055
(2018/06/15)
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- Room temperature decarboxylative cyanation of carboxylic acids using photoredox catalysis and cyanobenziodoxolones: a divergent mechanism compared to alkynylation
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The one-step conversion of aliphatic carboxylic acids to the corresponding nitriles has been accomplished via the merger of visible light mediated photoredox and cyanobenziodoxolones (CBX) reagents. The reaction proceeded in high yields with natural and non-natural α-amino and α-oxy acids, affording a broad scope of nitriles with excellent tolerance of the substituents in the α position. The direct cyanation of dipeptides and drug precursors was also achieved. The mechanism of the decarboxylative cyanation was investigated both computationally and experimentally and compared with the previously developed alkynylation reaction. Alkynylation was found to favor direct radical addition, whereas further oxidation by CBX to a carbocation and cyanide addition appeared more favorable for cyanation. A concerted mechanism is proposed for the reaction of radicals with EBX reagents, in contrast to the usually assumed addition elimination process.
- Le Vaillant, Franck,Wodrich, Matthew D.,Waser, Jér?me
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p. 1790 - 1800
(2017/03/09)
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- Decarboxylative alkynylation and cyanation of carboxylic acids using photoredox catalysis and hypervalent iodine reagents
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Alkynes and nitriles are important functional groups that serve as versatile building blocks in organic synthesis and find applications in material and medicinal sciences. A convenient and straightforward access to both classes of compounds under mild conditions is, therefore, highly desirable. Herein, we disclose the decarb-oxylative alkynylation and cyanation of broadly available carboxylic acids using photoredox catalysis and hyper-valent iodine reagents. Choices of both catalysts and reagents were crucial. Computational and experimental studies revealed two different possible mechanisms that are dictated by the oxidation potential of the reagents: radical for alkynylation, ionic for cyanation.
- Le Vaillant, Franck,Waser, Jér?me
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p. 226 - 230
(2017/06/27)
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- INDUCIBLE NITRIC OXIDE SYNTHASE DIMERIZATION INHIBITORS
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The present invention relates to compounds and methods useful as inhibitors of nitric oxide synthase. Certain compounds of the subject invention have the following structural formula: wherein T, X, and Y are independently selected from the group consisting of CR4, N, NR4, S, and O; U is selected from the group consisting of CR10 and N; V is selected from the group consisting of CR4 and N; W and W' are independently selected from the group consisting of CH2, CR7R8, NR9, O, N(O), S(O)q and C(O); n, m and p are independently an integer from 0 to 5; q is 0, 1, or 2; and other substituents are as defined herein. Other compounds of the subject invention have structural formulas as defined herein. Also disclosed herein are pharmaceutical compositions comprising the compounds of the subject invention
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Page/Page column 66
(2010/11/08)
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