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

Abstract

New N-alkyl(trifluoromethyl)sulfonyl 1,4-benzoquinone monoimines were synthesized, and their thiocyanation gave 5-alkyl(trifluoromethyl)sulfonylamino-1,3-benzoxathiol-2-ones. An intermediate thiocyanation product, 5-trifluoromethylsulfonylamino-1,3-benzoxathiol-2-imine, was isolated for the first time. † Deceased. N-Substituted p-quinone imines were reported for the first time more than hundred years ago. Their N-aryl [1,2], N-acyl [3], N-arylsulfonyl [4][5][6][7], N-arylsulfanyl [8], N-arylsulfinyl [9], N-(N-arylsulfonylbenzimidoyl) [10], and N-arylaminocarbonyl derivatives [11] were synthesized and used for the preparation of various compounds possessing fungicidal, bactericidal [12], and anticancer activity [13], as well as of vulcanizing agents for rubber [14], corrosion inhibitors [15], and powerful dehydrating agents [16]. On the other hand, organic compounds with fluorine-containing substituents also find increasing application as medicines, pesticides, dyes, and monomers for heatresistant polymers [17].The reactivity of N-arylsulfonyl 1,4-benzoquinone monoimines was studied in sufficient detail. 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].Adams and Looker [4] previously described the only representative of N-alkylsulfonyl 1,4-benzoquinone monoimines, N-methylsulfonyl-1,4-benzoquinone monoimine, whose reactivity was not studied. We previously presumed that superstrong electronwithdrawing substituents can be obtained by replacement of oxygen in various groups by an =NSO 2 CF 3 moiety [33]. With p-fluorobenzaldehyde as an example we showed that replacement of the carbonyl oxygen atom in the aldehyde group (CH=O is a mediumstrength electron-withdrawing group, σ p = 0.59) by =NSO 2 CF 3 gives CH=NSO 2 CF 3 (σ p = 1.00) which is a considerably stronger electron acceptor than nitro group (σ p = 0.78), and its strength approaches that of SO 2 CF 3 group (σ p = 1.04). Replacement of the oxygen atom in carboxylic acid azides, amides, and oximes by =NSO 2 CF 3 group made it possible to perform previously unknown rearrangements, such as aza-Curtius, aza-Hofmann, and aza-Lossen reactions [34]. We believed that replacement of oxygen atom in quinones by considerably more acceptor =NSO 2 CF 3 group, as in other cases, should give rise to unusual properties of N-trifluoromethylsulfonyl 1,4-benzoquinone monoimines.The goal of the present work was to synthesize new N-alkyl(trifluoromethyl)sulfonyl 1,4-benzoquinone monoimines, study their reactions with potassium thiocyanate, and compare the reactivities of N-arylsulfonyl, N-alkylsulfonyl, and N-trifluoromethylsu...

Reactions of N-aryl(methyl, trifluoromethyl)sulfonyl-1,4-benzoquinone monoimines with sodium sulfinates

“…The singlet of the trifl uoromethylsulfonyl group of compounds Va-Vn appeared in the 19 F NMR spectra in the region δ -74.8 to -76.4 ppm. It is known that in the spectrum of N-(4-hydroxyphenyl)-1,1,1-trifl uoromethanesulfonamides it is observed in the region δ -75.1 to -76.4 ppm [3], and in the spectrum of N-phenyl-N-(trifl uoromethylsulfonyl)-1,1,1-trifl uoromethanesulfonamide, at -78.9 ppm [12]. In the spectra of the products of the addition at the oxygen atom and of products of the 6,3-addition the singlets of the trifl uoromethylsulfonyl group are observed in the region δ -75.6 to -75.7 and -75.3 to -75.4 ppm respectively, and of the products of the addition at the nitrogen atom VIIIa, VIIIb, at -75.8 to -75.9 ppm.…”

“…The fl uorine signals in the 19 F NMR spectra of the products of 1,4-addition of sodium sulfi nates to quinine imines IIa−IIf were attributed based on the published data on the chemical shifts of the =NSO 2 CF 3 group in various compounds [3,12]. The singlet of the trifl uoromethylsulfonyl group of compounds Va-Vn appeared in the 19 F NMR spectra in the region δ -74.8 to -76.4 ppm.…”

“…N-Methyl(trifl uoromethyl)sulfonyl-1,4-benzoquinone monoimines Ia-Ii, IIa-IIi were synthesized by procedures described in [3,10]. The results of reactions between benzoquinone monoimines Ia-If, IIa-IIf and sodium sulfi nates IIIa-IIIf are presented in Scheme 1.…”

“…This choice of conditions is due to the higher reactivity towards nucleophiles of N-trifl uoromethylsulfonyl-1,4-benzoquinone monoimines IIa-IIf: they react at room temperature and even at cooling [3], in contrast to formerly studied N-arylsulfonyl-1,4-benzoquinone monoimines whose reactions with arylsodium sulfi nates proceed only in boiling acetic acid [5][6][7][8][9].…”

“…By replacing the carbonyl group of the p-benzoquinone with the =NSO 2 CF 3 group N-trifl uoromethylsulfonyl-1,4-benzoquinone monoimines were synthesized [3] that are structural analogs of N-methyl(aryl)sulfonyl-1,4-benzoquinone monoimines. The van der Waals radii of the methyl and trifl uoromethyl groups have close values (0.21 and 0.18 nm [4]), therefore the reactivity difference of these compounds should be governed mainly by different electronic effects of these substituents.…”