V. V. Astakhova

Oxidative addition of trifluoromethanesulfonamide to vinylcyclohexane and p-chlorostyrene

Trifluoromethanesulfonamide reacted with vinylcyclohexane in the system t-BuOCl-NaI to give a mixture of 2,6-dicyclohexyl-1,4-bis(trifluoromethylsulfonyl)piperazine and 2-iodo-1-cyclohexylethanol. Conformational behavior of the heterocyclization product was studied by dynamic NMR. The reaction of p-chlorostyrene with trifluoromethanesulfonamide under analogous conditions produced the corresponding bis-adduct, N-[2-(4-chlorophenyl)-2-(trifluoromethylsulfonylamino)ethyl]trifluoromethanesulfonamide and 1-(4-chlorophenyl)-2-iodoethanol. A probable reaction mechanism was proposed, which rationalizes difference in the behavior of the examined alkenes.

Unususal reaction of trifluoromethanesulfonamide with diallyl sulfide

Earlier, we have studied the addition of trifl uoromethanesulfonamide (trifl amide) to a series of alkenes and dienes under oxidative conditions [1–5]. In continuation of these studies in this paper we report on the reaction of trifl amide with diallyl sulfi de in acetonitrile in the oxidative system (t-BuOCl + NaI). Prior to our research, no information was available on the addition of sulfonamides to dienes under oxidative conditions. The molecule of diallyl sulfi de has three reaction centers liable to electrophilic attack: two π-bonds С=С and atom S(II). It turned out that the presence of the sulfur atom fundamentally alters the behavior of diallyl sulfi de in the reaction with trifl amide under oxidative conditions compared to the studied alkenes and dienes [1–5]. In the reaction with trifl amide in the system (t-BuOCl + NaI) the double bonds С=С remained intact, and the only product obtained in a good yield was the product of oxidative addition of two trifl amide residues to the sulfur atom with the formation of two new σ-bonds S–N, N,N’-(diprop-2-en-1-yl-λ4sulfanediyl)bis(1,1,1-trifl uoromethanesulfonamide)

Oxidative addition of trifluoromethanesulfonamide to cycloocta-1,3-diene. Ring contraction rearrangement

Unlike cycloocta-1,5-diene which undergoes heterocyclization in the reaction with trifluoromethanesulfonamide in the presence of t-BuOCl and NaI, its conjugated isomer, cycloocta-1,3-diene (I) does not react with trifluoromethanesulfonamide under the same conditions. Only unreacted trifluoromethanesulfonamide was isolated from the tarry reaction mixture obtained at both room temperature and on cooling (0°C) [1]. Surprisingly, by carrying out the reaction at –30°C we isolated trifluoro-N-(3-formylcyclohept-2en-1-yl)methanesulfonamide (II) in a moderate yield (Scheme 1). a bicyclic 1,4-addition product, 9-tosyl-9-azabicyclo[4.2.1]non-7-ene [2]. The structure of amide II was proved by IR and H, C, and F NMR spectroscopy, including NOE and COSY (H–H, H–C) experiments. The signal of C (δC 23.6 ppm) was identified by the presence of a cross peak with the proton signal at δ 2.85 ppm and observation of NOE between the latter and aldehyde proton. The vinylic proton (2-H) displayed NOEs with the aldehyde proton and those in the NH and NCH groups, and the NH proton also showed NOEs with protons on C (δ 1.81 and 2.09 ppm). The C=C–C=O fragment was assigned s-trans configuration on the basis of the difference between the νC=O and νC=C vibration frequencies in the IR spectrum (Δ ν = 23 cm). It is known that the Δ ν value for s-trans conformers is smaller than 60 cm and that it exceeds 70 cm for s-cis configuration [3]. Two mechanisms of formation of aldehyde II are possible. The first of these (Scheme 2) involves ring contraction in intermediate cation A. An alternative mechanism (Scheme 3) implies intermediate formation Scheme 1. ISSN 1070-4280, Russian Journal of Organic Chemistry, 2014, Vol. 50, No. 3, pp. 445–446.

Oxidative cycloaddition of electron-deficient arenesulfonamides to hexa-1,5-diene

The reaction of electron-deficient arenesulfonamides 4-XC6H4SO2NH2 (X = Cl, NO2) with hexa-1,5-diene in the oxidative system t-BuOCl-NaI afforded cis- and trans-isomeric 1-(arenesulfonyl)-2,5-bis(iodomethyl)pyrrolidines. The diastereoisomers were separated, and their structure was determined by NMR spectroscopy and X-ray analysis. No further cyclization of these compounds into 3,8-diazabicyclo[3.2.1]-octanes was observed.

Reaction of trifluoromethanesulfonamide with heterodienes under oxidation conditions

Reactions of trifluoromethanesulfonamide with divinyl sulfone, divinyl sulfoxide, divinyl sulfide, diphenyl sulfide, vinyl allyl and diallyl ethers was investigated in the presence of oxidation system t-BuOCl + NaI. The reaction with divinyl sulfone afforded a product of 1,5-heterocyclization, 2,6-diiodo-4-[(trifluoromethyl) sulfonyl]thiomorpholine 1,1-dioxide. The same product was obtained in the reaction with divinyl sulfoxide apparently due to its preliminary oxidation to sulfone. In reactions with divinyl sulfide and unsaturated ethers only the oxidation of substrates was observed accompanied with strong tarring; the products of a reaction with trifluoromethanesulfonamide were absent. With diphenyl sulfide a product was formed resulting from the oxidation at the sulfur atom [S(II) → S(IV)], N-(diphenyl-λ4-sulfanylidene)trifluoromethanesulfonamide.

Oxidative addition/cycloaddition of arenesulfonamides and triflamide to N-allyltriflamide and N,N-diallyltriflamide

N-Allyltriflamide adds triflamide in the oxidative system (t-BuOCl + NaI) to give N,N′,N′′-propane-1,2,3-triyltris(triflamide), while under the same conditions arenesulfonamides as well as trifluoroacetamide diastereoselectively give the product of chlorination/dimerization, (2R,5S)-2,5-bis(chloromethyl)-1,4-bis[(trifluoromethyl)sulfonyl]piperazine. N,N-Diallyltriflamide reacted with triflamide affords the products of iodotriflamidation of one or two CC bonds, and the product of intramolecular iodotriflamidation, 3,7-diiodo-1,5-bis[(trifluoromethyl)sulfonyl]-1,5-diazocane, and 3,7,9-tris[(trifluoromethyl)sulfonyl]-3,7,9-triazabicyclo[3.3.1]nonane. In contrast, with arenesulfonamides and trifluoroacetamide, N,N-diallyltriflamide gives the products of iodoamidation or/and iodochlorination at only one double bond.

Oxidative iodination of N-propargyltriflamide

The reaction of trifluoromethanesulfonamide with trifluoro-N-(prop-2-yn-1-yl)methanesulfonamide in the system t-BuOCl–NaI afforded N-[(2E)-2,3-diiodoprop-2-en-1-yl]trifluoromethanesulfonamide.

Reactions of N-Allyl- and N,N-Diallyltrifluoromethanesulfonamides with Carboxylic Acid Amides under Oxidizing Conditions

Reactions of acetamide and benzamide with N-allyltrifluoromethanesulfonamide in the presence of t-BuOCl–NaI afforded exclusively 2,5-bis(chloromethyl)-1,4-bis(trifluoromethanesulfonyl)piperazine. Analogous reaction with N,N-diallyltrifluoromethanesulfonamide gave mixed halogenation product at only one C=C double bond of the substrate.

Oxidative trifluoroacetamidation of (1 E ,3 E )-1,4-diphenylbuta-1,3-diene and 1,1,4,4-tetraphenylbuta-1,3-diene

Reactions of trifluoroacetamide with (1E,3E)-1,4-diphenylbuta-1,3-diene and 1,1,4,4-tetraphenylbuta-1,3-diene in the oxidative system t-BuOCl–NaI have been studied. The reaction with (1E,3E)-1,4-diphenylbuta-1,3-diene afforded three products, N,N′-(phenylmethylene)bis(trifluoroacetamide), 3-chloro-4-iodo- 2,5-diphenyl-1-(trifluoroacetyl)pyrrolidine, and trifluoro-N-[(3E)-2-hydroxy-1,4-diphenylbut-3-en-1-yl]acetamide, with a high overall yield. 1,1,4,4-Tetraphenylbuta-1,3-diene failed to react with trifluoroacetamide.

Intra- and intermolecular hydrogen bonding in solutions of N-(2-hydroxy-3,8-diiodocyclooctyl)trifluoroacetamide and N-(4-iodo-2,2,5,5-tetramethyltetrahydrofuran-3-yl)trifluoroacetamide

The methods of IR spectroscopy and quantum chemistry (B3LYP/DGDZVP) were applied to investigation of the types of self-associates formed in solutions of N-(2-hydroxy-3,8-diiodocyclooctyl)trifluoroacetamide and N-(4-iodo-2,2,5,5-tetramethyltetrahydrofuran-3-yl)trifluoroacetamide in CCl4 by means of hydrogen bonding. The ОН group of N-(2-hydroxy-3,8-diiodocyclooctyl)trifluoroacetamide participates in the formation of intramolecular hydrogen bond ОH···О=С, while chain dimers are formed due to interactions between the NH and С=О groups of the neighboring molecules. Due to the formation of the intramolecular bond, the dimers of N-(2-hydroxy-3,8-diiodocyclooctyl)trifluoroacetamide are energetically less stable than the chain dimer of N-(4-iodo-2,2,5,5-tetramethyltetrahydrofuran-3-yl)trifluoroacetamide.