I. V. Ushakova

Bromination-dehydrobromination/debromination of N-Methyl-N-(2-phenylethenyl)trifluoromethanesulfonamide

We have recently synthesized the first N-alkenylsubstituted trifluoromethanesulfonamide, N-methyl-N[(E)-2-phenylethenyl]trifluoromethanesulfonamide (I) [1]. With a view to obtain new trifluoromethanesulfonamide derivatives, we tried to synthesize adducts of I with various nucleophiles. However, compound I failed to react with methanol, ethanol, or diethylamine even on prolonged heating under reflux, but it readily took up bromine molecule in dioxane, and the resulting dibromo derivative readily underwent dehydrobromination by the action of alcoholic alkali (Scheme 1). 10.9 Hz), and a doublet at δ 6.58 ppm (J = 9.5 Hz) with a lower intensity. The intensity of the signal at 5.15 ppm was equal to the overall intensity of the signals at δ 6.51 and 6.58 ppm; the intensity ratio of the major and minor downfield signals was about 8 : 1. Assuming that the signal at δ 5.15 ppm is a superposition of two doublets corresponding to the downfield signals at δ 6.51 and 6.58 ppm, we can conclude that adduct II is a mixture of two diastereoisomers at a ratio of 8 : 1. These findings are consistent with the presence in the F NMR spectrum of II of two signals at δF –73.95 and –72.46 ppm with the same intensity ratio. Insofar as initial compound I is trans isomer [1], the major product should be stereoisomer IIa in agreement with the generally preferred trans-addition pattern. This is also supported by the results of HF/6-311G** calculations [2], according to which the energy of isomer IIa is lower by 1.3 kcal/mol than that of IIb. ISSN 1070-4280, Russian Journal of Organic Chemistry, 2013, Vol. 49, No. 6, pp. 924–926.

N , N ′-(hexa-2,4-diyne-1,6-diyl)bis(trifluoromethanesulfonamide)

Highly unsaturated trifluoromethanesulfonamide derivatives attract interest as building blocks in synthetic organic chemistry for the preparation of functionally substituted, heterocyclic, and other compounds. They are also interesting from the viewpoint of their structure due to possible tautomerism and effect of strong electron-withdrawing trifluoromethanesulfonyl group on tautomeric transformations.

Reactions of N-(Polychloroethylidene)arene-and - trifluoromethanesulfonamides with indoles

N-(Polychloroethylidene)arene-and -trifluoromethanesulfonamides reacted with indole and N-substituted indoles to give the corresponding N-[2,2-dichloro(or 2,2,2-trichloro)-1-(1H-indol-3-yl)ethyl]-substituted sulfonamides. Unlike N-(2,2,2-trichloroethylidene)trifluoromethanesulfonamide, less electrophilic N-(poly-chloroethylidene)arenesulfonamides failed to react with 1-(4-nitrophenyl)-1H-indole. Previously unknown N,N’-bis(2,2-dichloroethylidene)biphenyl-4,4’-disulfonamide reacted with 1-benzyl-1H-indole at both azomethine fragments. Likewise, reactions of 1,6-bis(1H-indol-1-yl)hexane and 1,4-bis(1H-indol-1-ylmethyl)-benzene with N-sulfonyl trichloroacetaldehyde imines involved both indole rings in the former.

Bromination of highly unsaturated trifluoromethanesulfonamide derivatives

The bromination of trifluoro-N-(prop-2-yn-1-yl)methanesulfonamide with molecular bromine gives a mixture of Z- and E-isomeric N-(2,3-dibromoprop-2-en-1-yl)trifluoromethanesulfonamides, regardless of the reaction conditions. Bromine adds to both triple bonds of trifluoro-N,N-bis(prop-2-yn-1-yl)methanesulfonamide, yielding a mixture of N-(2,3-dibromprop-2-en-1-yl)trifluoro-N-(prop-2-yn-1-yl)methanesulfonamide, N,N-bis(2,3-dibromoprop-2-en-1-yl)trifluoromethanesulfonamide, and trifluoro-N,N-bis(2,2,3,3-tetrabromopropyl) methanesulfonamide. Diacetylenic trifluoromethanesulfonamide derivative, N,N′-hexa-2,4-diyne-1,6-diylbis( trifluoromethanesulfonamide), reacts with bromine to afford N,N′-[(2E,4E)-2,3,4,5-tetrabromohexa-2,4-diene-1,6-diyl]bis(trifluoromethanesulfonamide) and isomeric N-(2,3-dibromoprop-2-en-1-yl)trifluoromethanesulfonamides resulting from reductive cleavage of the central C–C bond in the former.

N -benzyl- N -[( E )-2-phenylethenyl]trifluoromethanesulfonamide

In the search for an approach to N-vinyltriflamides with a free NH group TfNHCH=CHR (Tf = CF3SO2) N-(benzyl)-N-(2-bromo-2-phenylethenyl)triflamide TfN(Bn)CH=CHPh was synthesized through bromination-dehydrobromination of N-(benzyl)-N-(2-phenylethyl)triflamide. At removing the benzyl protecttion by the action of trifluoromethanesulfonic acid benzyl alcohol separated; however instead of the target N-styryltriflamide unexpectedly the product of its hydrogenation was obtained, N-(2-phenylethyl)triflamide. Obviously, the benzyl alcohol was the hydrogen donor, and the easy hydrogenation was facilitated by the high electrophilicity of the double bond in N-styryltriflamide because of strong electron-acceptor effect of the triflyl group.

13C-13C spin-spin coupling constants in structural studies: XLI. Stereochemical study on N-(polychloroethylidene)arenesulfonamides and N’-arylsulfonylformimidamides

The second-order polarization propagator approach (SOPPA) was used to calculate 13C-1H, 13C-13C, and 15N-1H coupling constants for a series of N-(polychloroethylidene)arenesulfonamides and N’-arylsulfonylformimidamides, and their configuration with respect to the C=N bond was determined by comparing the calculated data with the experimental values. All the examined compounds were found to exist in solution exclusively as the corresponding E isomers. The most favorable conformations and relative energies of the E and Z isomers in the gas phase were determined in terms of the second-order perturbation theory (MP2/6-311G**). N’-Arylsulfonylformimidamides are characterized by restricted internal rotation of the dialkylamino group about the C-N bond having an increased order.

Reaction of N,N-dichlorosulfonamides with tribromoethylene

Reaction of aryl-and trifluoromethanesulfonic acids N,N-dichloroamides with tribromoethylene led to the formation of a mixture of N-(2,2-dibromo-2-chloroethylidene)-and N-(2,2,2-tribromoethylidene)amides of the corresponding sulfonic acids. The azomethines ratio is governed by the reaction temperature.

Electronic structure and basicity of trifluoro-N-methyl-N-(2-phenylethenyl)methanesulfonamide

The electronic structures and basicities of trifluoro-N-methyl-N-(2-phenylethenyl)methanesulfonamide, N-methyl-2-phenylethenamine, trifluoro-N-methylmethanesulfonamide, and their C-, N-, and O-protonated forms and H-complexes were studied at the B3LYP/6–311+G** and MP2/cc-pVTZ levels of theory. The basicity of the double bond in trifluoro-N-methyl-N-(2-phenylethenyl)methanesulfonamide is much lower than that in N-methyl-2-phenylethenamine, and its protonation is possible only in trifluoromethanesulfonic acid.

Synthesis and transformations of bis(polychloroethylideneaminosulfonyl)- and bis(polychloroethylideneaminosulfonyl)-substituted derivatives of biphenyl, diphenyl oxide, and diphenylmethane

Reactions of N,N,N′,N′-tetrachlorobiphenyl-4,4′-disulfonamide, 4,4′-methylenebis(N,N-dichlorobenzenesulfonamide), and 4,4′-oxybis(N,N-dichlorobenzenesulfonamide) with 1,2-dichloroethylene and trichloroethylene open convenient synthetic approach to highly electrophilic bissulfony limines of dichloroacetic aldehyde and chloral: N,N′-bis(polychloroethylidene)biphenyl-4,4′-disulfonamides, 4,4′-methylenebis[N-(polychloroethylidene)benzenesulfonamides] and 4,4′-oxybis[N-(polychloroethylidene)benzenesulfonamides]. The synthetic opportunities of the bisazomethines obtained were demonstrated by examples of their reactions with water, methanol, chloroacetamide, and toluene where products of O-, N-nucleophiles addition to the azomethine bond and products of C-amidoalkylation of aromatic compound with imines were formed.

The reaction of the N,N-dichloroamide of 5-chloro-2-thienylsulfonic acid with trichloroethylene as a convenient synthetic route to a series of trichloroethylamides of 5-chloro-2-thienylsulfonic acid

N-(2,2,2-Trichloroethylidene)-5-chlorothien-2-ylsulfonamide, the first representative of the polyhaloalkylidenamides of heterylsulfonic acids, has been synthesized by the reaction of N,Ndichloro-5-chlorothien-2-ylsulfonamide with trichloroethylene and used as a regioselective Сamidoalkylating agent of aromatic compounds and in reactions with nucleophiles, forming a series of N-(2,2,2-trichloroethyl) amides of 5-chloro-2-thienylsulfonic acid.