Decarboxylative Radical Addition Research Articles

Visible-Light-Mediated Decarboxylative Radical Additions to Vinyl Boronic Esters: Rapid Access to γ-Amino Boronic Esters.

The synthesis of alkyl boronic esters by direct decarboxylative radical addition of carboxylic acids to vinyl boronic esters is described. The reaction proceeds under mild photoredox catalysis and involves an unprecedented single‐electron reduction of an α‐boryl radical intermediate to the corresponding anion. The reaction is amenable to a diverse range of substrates, including α‐amino, α‐oxy, and alkyl carboxylic acids, thus providing a novel method to rapidly access boron‐containing molecules of potential biological importance.

Visible‐Light‐Mediated Decarboxylative Radical Additions to Vinyl Boronic Esters: Rapid Access to γ‐Amino Boronic Esters

AbstractThe synthesis of alkyl boronic esters by direct decarboxylative radical addition of carboxylic acids to vinyl boronic esters is described. The reaction proceeds under mild photoredox catalysis and involves an unprecedented single‐electron reduction of an α‐boryl radical intermediate to the corresponding anion. The reaction is amenable to a diverse range of substrates, including α‐amino, α‐oxy, and alkyl carboxylic acids, thus providing a novel method to rapidly access boron‐containing molecules of potential biological importance.

Visible-Light Photocatalytic Decarboxylative Alkyl Radical Addition Cascade for Synthesis of Benzazepine Derivatives.

A visible-light photocatalytic decarboxylative alkyl radical addition cascade reaction of acrylamide-tethered styrenes for the synthesis of benzazepine derivatives is described. This protocol features broad substrate scope, excellent functional group tolerance, and mild reaction conditions, affording the seven-membered rings in good yields. This method was also applied for efficient grafting of the benzazepine scaffold into the pharmaceutically active ursolic acid scaffold.

Sunlight-induced decarboxylative radical addition of carboxylic acids to electron-deficient alkenes using a millitube reactor

Abstract The use of a fluorinated ethylene propylene (FEP) millitube reactor significantly improved the efficiency of the photoinduced decarboxylative radical addition of aliphatic carboxylic acids to electron-deficient alkenes, producing the corresponding γ-amino acid derivative and macrocyclic lactone. These sunlight-induced photoreactions were achieved using a millitube reactor, even though the photosensitizer used in this system absorbs only UV light.

N -Acryloyl amino acid esters and peptides as radical acceptors in photoinduced decarboxylative radical reaction

The photoinduced electron transfer (PET) promoted decarboxylative radical additions of carboxylic acids using N-acryloyl amino acid esters and peptides as radical acceptors smoothly afforded the corresponding modified amino acids and peptides under mild reaction conditions. The radical additions of α-amino acids led to the formation of γ- and α-dipeptide, and peptides underwent peptide coupling via decarboxylation.

Decarboxylative radical addition of N-Boc-amino acids to acrylonitrile via photoinduced electron transfer using 1,4-dicyanonaphthalene

Decarboxylative radical addition of N-(t-butoxycarbonyl)amino acids to acrylonitrile was achieved by excitation of 1,4-dicyanonaphthalene. The photochemical decarboxylation was highly dependent on the dicyanoarenes used as electron acceptors and on addition of a base. The photoreaction proceeded smoothly to yield the decarboxylative adduct even in the presence of only a catalytic amount of 1,4-dicyanonaphthalene.

ChemInform Abstract: Further Observations on the Thermal Stability of N-Hydroxy-2- thiopyridone Esters: Improved Decarboxylative Radical Additions to Olefins.

Decarboxylative radical addition onto olefins via thiohydroxamate esters can be considerably improved by heating and irradiating the reaction mixture; compound 10 can thus be obtained in 64% yield in one operation from acid chloride 6.

Decarboxylative radical addition to vinylsulphones and vinylphosphonium bromide: Some further novel transformations of geminal (pyridine-2-thiyl) phenylsulphones.

Irradiation of O-acyl derivatives 1 of N-hydroxy-2-thiopyridone with visible light in the presence of phenyl vinyl sulphone or vinyl triphenylphosphonium bromide leads to the corresponding adducts 8 and 9 which can undergo a wide variety of further transformations.

Further observations on the thermal stability of N-hydroxy-2-thiopyridone esters: improved decarboxylative radical additions to olefins

Decarboxylative radical addition onto olefins via thiohydroxamate esters can be considerably improved by heating and irradiating the reaction mixture; compound 10 can thus be obtained in 64% yield in one operation from acid chloride 6.

ChemInform Abstract: The Invention of Radical Reactions. Part 18. Decarboxylative Radical Addition to Arsenic, Antimony, and Bismuth Phenylsulfides. A Novel Synthesis of Noralcohols from Carboxylic Acids.

AbstractThe reaction of a wide range of thiohydroxamate esters such as (I) with the tris(phenylsulfide) (II) is studied.

The invention of radical reactions. Part XVIII. Decarboxylative radical addition to arsenic, antimony, and bismuth phenylsulphides - a novel synthesis of nor-alcohols from carboxylic acids

Carbon centered radicals obtained by decarboxylative transformation of suitable thiohydroxamate esters react with group Va trisphenyl-sulphides to give intermediates of general formula R-M(SPh) 2 (M = As, Sb, Bi). These react spontaneously with air to give the corresponding alcohols. This procedure is especially useful in the case where M=Sb. It is thus sufficient to stir the thiohydroxamate ester with tris(phenylthio)-antimony under air to obtain the nor alcohol directly and in high yield. The intermediate organometalloid could also be oxidised with nitrogen dioxide to give the expected nitroalkane albeit in only modest yield. The corresponding organobismuth intermediate derived from 3, 3-diphenylpropionic acid could actually be isolated thereby providing strong evidence for the proposed mechanism.

Some further novel transformations of geminal (pyridine-2-thiyl) phenylsulphones

Geminal (pyridine-2-thiyl) phenylsulphones, obtained by decarboxylative radical addition of O-acyl derivatives of N-hydroxy- 2-thiopyridone onto phenyl vinyl sulphone, undergo a wide variety of further transformations when subjected to sodium telluride or to organoaluminum reagents.

ChemInform Abstract: Decarboxylative Radical Addition onto Protonated Heteroaromatic Systems Including Purine Bases.

AbstractThe esters (III), prepared from N‐hydroxypyridine‐2‐thione (II) and the acids (I), are photolytically cleaved in the presence of heterocycles such as (IV) and camphorsulfonic acid to transfer the cycloalkyl moiety R1.

The invention of radical chain reactions: Part XIV. A decarboxylative radical addition to quinones

Irradiation of esters 3 derived from aliphatic or alicyclic carboxylic acids and N-hydroxy-2-thiopyridone in the presence of various quinones gives high yields of the corresponding adducts (e.g. 9 ) with net loss of carbon dioxide.

Decarboxylative radical addition onto protonated heteroaromatic systems including purine bases

Irradiation of esters 2 derived from carboxylic acids and N -hydroxypyridine-2-thione 1 in the presence of anhydrous camphorsulphonic acid and various heteroaromatic systems including purines affords the corresponding adducts in moderate to good yield.