Thiocyanation of N-arylsulfonyl-, N-aroyl-, and N-[(N-arylsulfonyl)benzimidoyl]-1,4-benzoquinone imines

Synthesis and thiocyanation of N-alkyl(trifluoromethyl)sulfonyl 1,4-benzoquinone monoimines

“…Thiocyanation of 2,6-disubstituted 1,4-benzoquinone monoimines was accompanied by their reduction to the corresponding aminophenols [20], indicating that the reaction with thiocyanate ion is regioselective (1,4-addition). We performed thiocyanation of N-alkylsulfonyl and N-trifluoromethylsulfonyl 1,4-benzoquinone monoimines IVa-IVh and VIIa-VIIg with potassium thiocyanate in a mixture of acetic acid with chloroform at different temperatures.…”

“…We previously showed [20] that reactions of N-aroyl, N-arylsulfonyl, and N-(N-arylsulfonylbenzimidoyl) 1,4-benzoquinone monoimines, i.e., compounds characterized by a higher redox potential than N-aryl 1,4-benzoquinone monoimines [36,38], with thiocyanate ion lead to N-substituted 5-amino-1,3-benzoxathiol-2-ones. The product structure suggests addition of thiocyanate ion by the sulfur atom with formation of intermediate thiocyanate A.…”

“…In the present work we examined reactions of N-alkylsulfonyl and N-trifluoromethylsulfonyl 1,4-benzoquinone monoimines with potassium thiocyanate. This reaction is one of the most studied transformations of N-substituted 1,4-quinone imines [18][19][20], so that it was possible to compare the behavior of the newly synthesized compounds with the behavior of previously studied N-arylsulfonyl 1,4-benzoquinone monoimines. Thiocyanate ion SCN -is a soft ambident nucleophile capable of reacting by either sulfur or nitrogen atom [37].…”

“…Their reactions with potassium thiocyanate [18-20], sodium arenesulfinates [7, 21, 22], sodium azide [7, 23], hydrogen halides [4, 24], halogens [25], aromatic amines [7, 26], phenols and naphthols [5, 27], dialkyl [7, 28, 29] and trialkyl phosphites [29, 30], aryl-and acylhydrazines [31], and alcohols [6,7,22,32] were studied. It was found that the size and electron-withdrawing power of the substituent on the nitrogen atom strongly affect the reactivity of N-substituted p-quinone imines [18][19][20][21][22].…”

“…Thiocyanate ion SCN -is a soft ambident nucleophile capable of reacting by either sulfur or nitrogen atom [37]. Depending on the substituent on the nitrogen atom, benzoquinone imines can react with thiocyanate ion in both directions [18,20].…”