Reaction of N-acyl-and N-[N-arylsulfonylbenz(acet)imidoyl]-1,4-benzoquinone monoimines with hydrazoic acid

N-Aroyl-3,5-dimethyl-and N-[N-arylsulfonylbenz(acet)imidoyl]-3,5-dimethyl-1,4-benzoquinone monoimines react with hydrazoic acid according to the 1,4-addition pattern. N-Acyl-2,3,5,6-tetrachloro-1,4-benzoquinone monoimines take up hydrazoic acid at the double C=N bond (1,2-addition).     

Reactions of N-substituted 2,6(3,5)-dialkyl-1,4-benzoquinone imines with arenesulfinic acids

The regioselectivity in the reactions of N-arylsulfonyl-2,6-dialkyl-1,4-benzoquinone imines with arenesulfinic acids (1,6-, 6,1-, or 6,3-addition) is determined by steric factor, while in the reactions of N-aroyl-1,4-benzoquinone imines electronic effect of substituents in the quinoid ring is crucial. The reactions of N-arylsulfonyl-3,5-dimethyl-1,4-benzoquinone imines with arenesulfinic acids follow mainly the 1,4-addition pattern. N-(N-Arylsulfonylbenzimidoyl)-1,4-benzoquinone imines are capable of reacting in a way similar to both N-arylsulfonyl and N-aroyl derivatives.     

Reaction of N-arylcarbamoyl-1,4-benzoquinone imines with sodium azide

N-Arylcarbamoyl-1,4-benzoquinone imines reacted with sodium azide in completely regioselective fashion according to the 1,4-addition pattern with formation of 1-(3-azido-4-hydroxyphenyl)-3-arylureas. The reaction of N-arylcarbamoyl-2,6-dichloro-3,5-dimethyl-1,4-benzoquinone imines with sodium azide afforded N-arylcarbamoyl-2,6-diazido-3,5-dimethyl-1,4-benzoquinone imines as a result of nucleophilic substitution of the chlorine atoms.     

Reaction of N-acetyl- and N-[1-(arylsulfonylimino)ethyl]-1,4-benzoquinone imines with sodium arenesulfinates

N-Acetyl- and N-[1-(arylsulfonylimino)ethyl]-1,4-benzoquinone imines having no substituent in the 2- and/or 6-position of the quinoid ring react with sodium arenesulfinates preferentially according to the 1,4-addition pattern. The presence of an ArSO₂N group favors radical ion reaction with formation of 1,6-addition products.     

Reaction of some <Emphasis Type="Italic">N</Emphasis>-substituted 1,4-benzoquinone imines with sodium azide

The reactions of N-(arenesulfinyl)-1,4-benzoquinone imines with sodium azide afforded the corresponding N-(arylsulfanyl)-2-azido-1,4-benzoquinone imines via 1,4-addition of azide ion and subsequent intramolecular oxidation–reduction.     

Reaction of N-phenyl(benzylidene,phenoxy)acetyl-1,4-benzoquinone imines with sodium azide

N-Phenyl(benzylidene, phenoxy)acetyl-1,4-benzoquinone imines reacted with sodium azide to give the corresponding 1,4-addition products, N-(4-hydroxyphenyl) carboxamides. Quantum chemical calculations showed that the initial step in the examined reaction is addition of azide ion to neutral quinone imine molecule.     

Thiocyanation of <Emphasis Type="Italic">N</Emphasis>-arylsulfonyl-, <Emphasis Type="Italic">N</Emphasis>-aroyl-, and <Emphasis Type="Italic">N</Emphasis>-[(<Emphasis Type="Italic">N</Emphasis>-arylsulfonyl)benzimidoyl]-1,4-benzoquinone imines

Reactions of thiocyanate ion with N-aroyl-, N-arylsulfonyl-, and N-(N-arylsulfonylbenzimidoyl)-1,4-benzoquinone imines follow the 1,4-addition pattern, and the adducts undergo intramolecular cyclization to give the corresponding N-substituted 5-amino-1,3-benzoxathiol-2-ones as final products.     

Comparison of preparation methods of N-arylsulfinyl-1,4-benzoquinone monoimines

Advantages and shortcomings were discussed of three procedures for preparation N-arylsulfinyl-1,4-benzoquinone imines: the reaction of arenesulfenyl chlorides with 1,4-benzoquinone oximes, the oxidation of N-arylthio-1,4-benzoquinone imines, and the reaction of arylsulfinyl chlorides with p-aminophenols followed by oxidation. A series of new N-arylsulfinyl-1,4-benzoquinone imines was obtained.     

Reaction of N-substituted 2,5-dialkyl-1,4-benzoquinone imines with arenesulfinic acids

Reactions of N-aroyl-, N-arylsulfonyl-, and N-(N-arylsulfonylbenzimidoyl)-2,5-dialkyl-1,4-benzoquinone imines with sodium arenesulfinates in acetic acid gave the corresponding 1,4-, 6,1-, and 1,6-addition products. Variation of the size and donor power of substituents in positions 2 and 5 of the quinoid ring almost does not affect the ratio of the addition products, which is determined mainly by the nature of substituent on the nitrogen atom.     

Reaction of N-arylcarbamoyl-1,4-benzoquinone imines with sodium arenesulfinates

N-Arylcarbamoyl-1,4-benzoquinone imines possessing at least one free ortho position with respect to the carbonyl carbon atom in the quinoid ring react with sodium arenesulfinates according to the nucleophilic 1,4-addition pattern with complete regioselectivity. If both ortho positions are occupied, the reaction gives a mixture of products where the major ones are 1,6- and 6,1-adducts formed according to the radical ion mechanism.     

Photocatalytic Conversion of Benzyl Alcohols/Methyl Arenes to Aryl Nitriles via H-Abstraction by Azide Radical

This report presents the visible-light-assisted synthesis of aryl nitriles from easily accessible alcohols or methyl arenes in the presence of O₂. Organic photoredox catalyst, 4CzIPN (1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene), induces single electron transfer (SET) from azide N₃⁻ and generates azide radical N₃⋅.The photogenerated N₃⋅ abstracts H atom from α-C−H bond of benzylic system, which provides aldehyde and hydrazoic acid (HN₃) in situ. This reaction subsequently forms azido alcohol intermediate that transforms into nitrile with the assistance of triflic acid (Brønsted acid). A range of alcohols and methyl arenes successfully underwent cyanation at room temperature with good to excellent yields and showed good functional group tolerance.     

Halogenation of N-substituted p-quinone imines and p-quinone oxime esters: IV. Chlorination and bromination of N-arylsulfonyl-2(3)-methyl(2-chloro)-1,4-benzoquinone monoimines

The addition of halogens to N-arylsulfonyl-1,4-benzoquinone imines, which exist in a solution as Z and E isomers, is controlled by the steric factor. Z-E Isomerization strongly affects the stability of cyclohexene structures formed by halogenation of 1,4-benzoquinone imines. The halogenation of N-arylsulfonyl-1,4-benzoquinone imines was found to be accompanied by prototropic rearrangement.     

Reaction of <Emphasis Type="Italic">N</Emphasis>-chloro-1,4-benzoquinone imines with thiols

N-Chloro-1,4-benzoquinone imines reacted with arenethiols to give different products, depending on the conditions and initial quinone imine structure. N-(Arylsulfanyl)-1,4-benzoquinone imines were obtained as a result of nucleophilic substitution of the chlorine atom, and 1,4-benzoquinone imines containing an aryl-sulfanyl substituent in the quinoid ring were formed according to the radical mechanism. The reactions of N-chloro-1,4-benzoquinone imines with heterocyclic thiols afforded only the corresponding chlorine substitution products.     

Thiocyanation of N-arenesulfonyl-N′-aroyl-1,4-benzoquinone diimines

The reaction of N-arenesulfonyl-N′-aroyl-1,4-benzoquinone diimines with potassium thiocyanate in glacial acetic acid occurs as 1,4-addition of thiocyanate ion by the sulfur atom to the quinoid ring in the meta position with respect to the aroyl group. The addition products, N-[4-(arenesulfonamido)-3-thiocyanatophenyl]-benzamides, partially undergo intramolecular cyclization to N-(2-imino-3-arenesulfonyl-2,3-dihydro-1,3-benzothiazol-6-yl)benzamides whose hydrolysis yields 2-amino-6-benzamido-1,3-benzothiazol-3-ium arenesulfonates. The latter lose arenesulfonic acid with formation of N-(2-amino-1,3-benzothiazol-6-yl)benzamides on treatment with a mixture of methanol with water and acetic acid.     

Halogenation of N-substituted para-quinone monoimines and para-quinone monoximes ethers: IX. Halogenation of N-aroyl-2,6(3,5)-dimethyl-1,4-benzoquinone monoimines and their reduced forms

At the halogenation of N-aroyl-2,6(3,5)-dimethyl-1,4-benzoquinone imines we found the halogenation of methyl groups to occur. The bromination of N-aroyl-2,6-dimethyl-1,4-benzoquinone imines yielded 3,6-dibromo-2,6-dimethyl-5-aroyloxycyclohex-2-ene-1,4-diones due to the strong acceptor property of the ArCO group and high redox potentials of N-aroyl derivatives. In the chlorination of N-aroyl-3,5-dimethyl-1,4-benzoquinone imines the chlorine addition to the C=C bond of the quinoid ring proceeded both by the trans- and syn-scheme.     

Hydrohalogenation of N-acetyl(aroyl)-1,4-benzoquinone monoimines

New N-acetyl-1,4-benzoquinone monoimines alkyl-substituted in the quinoid ring were synthesized. The hydrohalogenation of N-acetyl(aroyl)-1,4-benzoquinone monoimines proceeds exclusively in keeping with the 1,4-addition. The hydrochlorination occurs along the ionic mechanism, in the hydrobromination grows the role of the radical mechanism.     

Reaction of N-arylsulfonyl-2(3)-arylsulfonylamino-substituted 1,4-benzoquinonimines with sodium arylsulfinates

N-Arylsulfonyl-3-arylsulfonylamino-substituted 1,4-benzoquinonimine reacts with sodium arylsulfinates regiospecifically along 1,4-addition scheme; N-tosyl-2-(tosylamino)-substituted 1,4-benzoquinonimine regioselectively affords products of 1,4- and 6,3-addition with the latter prevailing. Arylsulfinate anion enters predominantly in the para-position with respect to the ArSO₂NH group.     

Reactions of arylsulfinyl chlorides and <Emphasis Type="Italic">N</Emphasis>-(arylsulfonyl)arylsulfinimidoyl chlorides with <Emphasis Type="Italic">p</Emphasis>-aminophenols

In reactions of arylsulfinyl chlorides and N-(arylsulfonyl)arylsulfinimidoyl chlorides with p-aminophenols formed N-arylthio-1,4-benzoquinone imines, evidently through a stage of N-arylsulfinyl-4-aminophenols and N-(N-arylsulfonyl)arylsulfinylimidoyl-4-aminophenols that under the reaction conditions eliminate respectively H₂O and ArSO₂NH₂.     

Hydrohalogenation of <Emphasis Type="Italic">N</Emphasis>-[arylsulfonylimino(phenyl)methyl]-1,4-benzoquinone monoimines having alkyl substituents in the quinoid ring

Hydrohalogenation of N-[arylsulfonylimino(phenyl)methyl]-2,5(3,5)-dimethyl-1,4-benzoquinone monoimines follows exclusively the 1,4-addition pattern, whereas N-[arylsulfonylimino(phenyl)methyl]-2,6-dimethyl-1,4-benzoquinone monoimines take up hydrogen halides according to the 6,3-addition scheme.     

The features of the kinetics of radical reactions of quinone imines with 2-mercaptobenzothiazole

Kinetics of the reactions of N-phenyl-1,4-benzoquinone monoimine and N,N′-diphenyl-1,4-benzoquinone diimine with 2-mercaptobenzothiazole in chlorobenzene at T = 343 K has been studied by using kinetical spectrophotometry method (periodic spectral measurements and/or monitoring the wavelengths of the absorption band of quinone imines in the visible region). Two general features of the reactions, namely, radical mechanism and the existence of two steps were found. Kinetic features depend on the structure of a quinone imine. A reaction between N,N′-diphenyl-1,4-benzoquinone diimine and 2-mercaptobenzothiazole at first (initial) steps proceeds in an autoinhibition mode and has two independent channels, one of which being radical-chain. The addition of an initiator strongly accelerates the reaction only at the initial step, on completion of which the reaction rate decreases significantly and do not depend on the presence of the initiator. This testifies to the proceeding of the reaction by a non-chain mechanism subsequently to the initial step. The interaction involving N-phenyl-1,4-benzoquinone monoimine proceeds by a radical non-chain mechanism from the very beginning up to the end, and at the initial steps it proceeds in the autoaccelerating mode. The initiator has no influence on the reaction rate. For the process of the interaction of N,N′-diphenyl-1,4-benzoquinone monoimine and 2-mercaptobenzothiazole in the presence of 4-hydroxydiphenylamine, a radical mechanism was proposed, that serves to describe the kinetic features of the reaction and to obtain a quantitative estimation of some of its kinetic parameters.