The Reactions of Alkenes with Phenyl-N-triflylimino-λ3-iodane: Solvent and Oxidant Impact

The reactions of alkenes with phenyl-N-triflylimino-λ3-iodane PhI=NTf (1) have been studied in different conditions. In methylene chloride, in the presence of N-halosuccinimides, the products of mono and bis-triflamidation were obtained. In MeCN, the product of bromotriflamidation (with NBS) with solvent interception or of bis-triflamidation (with NIS) is formed. The reaction with trans-stilbene in acetonitrile with NBS gave rise to cyclization to 2-methyl-4,5-diphenyl-1-triflyl-4,5-dihydro-1H-imidazole. In contrast, with NIS as an oxidant, both in CH2Cl2 and MeCN, the major product was 2,3-diphenyl-1-triflylaziridine formed in good yield. With NBS, aziridine is also formed but as a minor product, the major one being a mixture of diastereomers of the product of bromotriflamidation. The reaction of compound 1 with vinylcyclohexane in methylene chloride affords the mixtures of regioisomers of the products of halotriflamidation, whereas in acetonitrile, the products of solvent interception and cyclization to the imidazoline are formed. A mechanism explaining the formation of all isolated products is proposed.


Introduction
N-Trifluoromethylsulfonyl (triflyl) substituted nitrogen compounds occupy a unique place in organic chemistry [1][2][3].The triflyl group is a very strong electron-withdrawing substituent responsible for the high NH-acidity of triflamides, their specific catalytic activity, the ability to form strong intra-and intermolecular hydrogen bonds, and a number of specific chemical properties.Low nucleophilicity and high NH-acidity allow triflamides to be used in a variety of organic reactions [1][2][3].
N-Triflylaziridines are of considerable interest from the viewpoint of their further transformations, allowing us to obtain structures that already contain the triflyl group.They have wide areas of application, such as nucleophilic ring opening to give N-protected alkyleneamines [4] and catalytic enantioselective alkylation of the methine carbon of carboxylic acids [5], which are used in the synthesis of tripodal tetradentate C3-symmetric amines [6].N-Triflylaziridines are also widely employed in the synthesis of ligands for metal complex catalysis [7][8][9][10][11][12][13][14].However, the methods of their synthesis meet significant difficulties precisely because of specific properties of the triflyl group.The necessity to use an unstable and explosive triflyl azide greatly complicates the reaction.Similar transformations of perfluorosulfonylazides and O-TMS ethers via the formation of N-perfluoromethylsulfonylaziridines give a set of α-[N-(peruoroalkanesulfonyl)]aminoketones and α-amino acids in good yields [16,17].UV activation of the reaction of butene-2 with the azide H(CF2)2O(CF2)2SO2N3 affords the corresponding aziridine in 61% yield [18].
The addition of N,N-dichloroalkanesulfonamide I(CF2)2O(CF2)2SO2NCl2 to styrene in the presence of EtONa/EtOH affords the corresponding aziridine in 49% yield.[24] A shortcoming of highly reactive N,N-dichloroalkanesulfonamides as reagents is their instability in air moisture and the need for special storage conditions [25].
More stable than triflylimino-λ 3 -bromane are triflylimino-λ 3 -iodanes.The N-triflyl-substituted analogs of the latter, N-triflylimino-λ 3 -iodanes ArI=NTf, were synthesized by the reaction of iodosobenzenes ArI=O with triflamide as late as in 2022 and used for amidation or imidation of phosphines and 1,3-diketones [26].However, in our recent work [27], we found no aziridines in the reaction of styrene with triflamide and iodosobenzene in the presence of iodine and CuCl.

Results and Discussion
Therefore, the synthesis of N-triflylaziridines remains a challenging task.Based on this, we have studied the reactions of alkenes with phenyl-N-triflylimino-λ 3 -iodane PhI=NTf (1) in different conditions.In methylene chloride, in the absence of oxidants, no reactions occurred with styrene, vinylcyclohexane, dimethyl(divinyl)silane, or tetramethyl(divinyl)siloxane; only the starting reagent 1 was recovered.Given that alkenes readily undergo triflamidation with solvent interception affording N-triflylamidines in the reaction with triflamide in the presence of N-halosuccinimides [27,28,29], we have studied the reactions of compound 1 with styrene in the presence of N-bromo (NBS) and N-iodosuccinimide (NIS).Depending on the solvent, the products of mono and bis-triflamidation of the double bond were obtained.Note that in the The necessity to use an unstable and explosive triflyl azide greatly complicates the reaction.Similar transformations of perfluorosulfonylazides and O-TMS ethers via the formation of N-perfluoromethylsulfonylaziridines give a set of α-[N-(peruoroalkanesulfonyl)] aminoketones and α-amino acids in good yields [16,17].UV activation of the reaction of butene-2 with the azide H(CF 2 ) 2 O(CF 2 ) 2 SO 2 N 3 affords the corresponding aziridine in 61% yield [18].
The addition of N,N-dichloroalkanesulfonamide I(CF 2 ) 2 O(CF 2 ) 2 SO 2 NCl 2 to styrene in the presence of EtONa/EtOH affords the corresponding aziridine in 49% yield [24].A shortcoming of highly reactive N,N-dichloroalkanesulfonamides as reagents is their instability in air moisture and the need for special storage conditions [25].
More stable than triflylimino-λ 3 -bromane are triflylimino-λ 3 -iodanes.The N-triflylsubstituted analogs of the latter, N-triflylimino-λ 3 -iodanes ArI=NTf, were synthesized by the reaction of iodosobenzenes ArI=O with triflamide as late as in 2022 and used for amidation or imidation of phosphines and 1,3-diketones [26].However, in our recent work [27], we found no aziridines in the reaction of styrene with triflamide and iodosobenzene in the presence of iodine and CuCl.

Results and Discussion
Therefore, the synthesis of N-triflylaziridines remains a challenging task.Based on this, we have studied the reactions of alkenes with phenyl-N-triflylimino-λ 3 -iodane PhI=NTf (1) in different conditions.In methylene chloride, in the absence of oxidants, no reactions occurred with styrene, vinylcyclohexane, dimethyl(divinyl)silane, or tetramethyl(divinyl)siloxane; only the starting reagent 1 was recovered.Given that alkenes readily undergo triflamidation with solvent interception affording N-triflylamidines in the reaction with triflamide in the presence of N-halosuccinimides [27][28][29], we have studied the reactions of compound 1 with styrene in the presence of N-bromo (NBS) and N-iodosuccinimide (NIS).Depending on the solvent, the products of mono and bis-triflamidation of the double bond were obtained.Note that in the products of halotriflamidation 3, 4 the triflamide residue adds to the α-carbon of the styrene molecule (Scheme 2).
The structure of the products and, hence, the regioselectivity of addition is proved by the presence of the NH signal at 5.76 (3) and 5.89 ppm (4), multiplets of the methine proton at 4.97 (3) and 4.78 ppm (4), and doublets of doublets at 3.74 (3) and 3.56 (4) of the methylene protons.
The structure of the products and, hence, the regioselectivity of addition is proved by the presence of the NH signal at 5.76 (3) and 5.89 ppm (4), multiplets of the methine proton at 4.97 (3) and 4.78 ppm (4), and doublets of doublets at 3.74 (3) and 3.56 (4) of the methylene protons.
In the presence of NIS, styrene reacts with N-triflylimino-λ 3 -iodane 1 in acetonitrile to give the product of bis-triflamidation TfNHCH(Ph)-CH2NHTf 7 in 54% yield, identical to that obtained earlier by the reaction with triflamide in the system t-BuOCl/NaI [30].
In continuation, we examined the reaction of compound 1 with some alkenes in the system I2/NaI/MeCN, which was successfully employed for the synthesis of N-tosylaziridines [31] (vide supra).In contrast, no aziridine was formed with compound 1, but only the aforementioned adduct 7 in a low yield of 25%.Under the same conditions, trans-stilbene and vinylcyclohexane did not react with compound 1.UV activation did not change the course of the reaction and only increased the yield of adduct 7 to 40%.
In the presence of NIS, styrene reacts with N-triflylimino-λ 3 -iodane 1 in acetonitrile to give the product of bis-triflamidation TfNHCH(Ph)-CH 2 NHTf 7 in 54% yield, identical to that obtained earlier by the reaction with triflamide in the system t-BuOCl/NaI [30].
In continuation, we examined the reaction of compound 1 with some alkenes in the system I 2 /NaI/MeCN, which was successfully employed for the synthesis of Ntosylaziridines [31] (vide supra).In contrast, no aziridine was formed with compound 1, but only the aforementioned adduct 7 in a low yield of 25%.Under the same conditions, trans-stilbene and vinylcyclohexane did not react with compound 1.UV activation did not change the course of the reaction and only increased the yield of adduct 7 to 40%.
In the presence of NIS, styrene reacts with N-triflylimino-λ 3 -iodane 1 in acetonitrile to give the product of bis-triflamidation TfNHCH(Ph)-CH2NHTf 7 in 54% yield, identical to that obtained earlier by the reaction with triflamide in the system t-BuOCl/NaI [30].
In continuation, we examined the reaction of compound 1 with some alkenes in the system I2/NaI/MeCN, which was successfully employed for the synthesis of N-tosylaziridines [31] (vide supra).In contrast, no aziridine was formed with compound 1, but only the aforementioned adduct 7 in a low yield of 25%.Under the same conditions, trans-stilbene and vinylcyclohexane did not react with compound 1.UV activation did not change the course of the reaction and only increased the yield of adduct 7 to 40%.
When the oxidant I2/NaI was replaced by NBS or NIS, the reaction of N-triflylimino-λ 3 -iodane 1 and trans-stilbene 8 in acetonitrile led to cyclization and formation of 2-methyl-4,5-diphenyl-1-triflyl-4,5-dihydro-1H-imidazole 9 (Scheme 4).The structure and composition of imidazole 9 was confirmed by IR, NMR spectroscopy, and high-resolution mass spectrometry (HRMS), which showed the molecular ion [M + H] + with m/z 369.08807 corresponding to C 17 H 16 F 3 N 2 O 2 S + .When using NIS as the oxidant, imidazole 9 was also formed but as a minor product, the major one being 2,3-diphenyl-1triflylaziridine 10 isolated in 78% yield (Scheme 5).The formation of aziridine 10 is the first case of the synthesis of N-sulfonylaziridines using N-sulfonylimino-λ 3 -iodanes as a source of the nitrogen group.
The structure and composition of imidazole 9 was confirmed by IR, NMR spectroscopy, and high-resolution mass spectrometry (HRMS), which showed the molecular ion [M + H] + with m/z 369.08807 corresponding to C17H16F3N2O2S + .When using NIS as the oxidant, imidazole 9 was also formed but as a minor product, the major one being 2,3-diphenyl-1-triflylaziridine 10 isolated in 78% yield (Scheme 5).The formation of aziridine 10 is the first case of the synthesis of N-sulfonylaziridines using N-sulfonylimino-λ 3 -iodanes as a source of the nitrogen group.The structure of aziridine 10 was proved by IR and NMR spectroscopy and confirmed by HRMS data.In particular, the values of the 1 JCH constants in the aziridine moiety are known to be much larger than in saturated aliphatic compounds and lie in the range of 170-180 Hz [32,33,34].The measured value of 1 JCH in product 10 is 177 Hz, which unambiguously proves its structure.The HRMS spectrum shows a molecular ion m/z at 328.06242, corresponding to the molecular formula C15H13F3NO2S + .
Earlier, it was shown that the reaction of styrenes with tosylamide in acetonitrile in the presence of t-BuOI leads to the substituted aziridines.[35] However, no aziridine is formed in the reaction with triflamide under the same conditions, but only the product of bis-triflamidation and disubstituted piperazine, which is, formally, the product of dimerization of the target aziridine [30].It can be assumed that the formation of piperazine is the result of relative instability of the intermediate 2-phenyl-1-triflylaziridine, because its analog, 2-phenyl-1-tosylaziridine is stable [30].Presumably, the stability of aziridine 10 is due to the presence of the second phenyl group stabilizing the molecule.In methylene chloride, the NIS-induced reaction also gives aziridine 10 in about the same yield, but with NBS it is the minor product, whereas the major product was identified to be N-(2-bromo-1,2-diphenylethyl)triflamide 11 (Scheme 6).The structure of aziridine 10 was proved by IR and NMR spectroscopy and confirmed by HRMS data.In particular, the values of the 1 J CH constants in the aziridine moiety are known to be much larger than in saturated aliphatic compounds and lie in the range of 170-180 Hz [32][33][34].The measured value of 1 J CH in product 10 is 177 Hz, which unambiguously proves its structure.The HRMS spectrum shows a molecular ion m/z at 328.06242, corresponding to the molecular formula C 15 H 13 F 3 NO 2 S + .
Earlier, it was shown that the reaction of styrenes with tosylamide in acetonitrile in the presence of t-BuOI leads to the substituted aziridines [35].However, no aziridine is formed in the reaction with triflamide under the same conditions, but only the product of bistriflamidation and disubstituted piperazine, which is, formally, the product of dimerization of the target aziridine [30].It can be assumed that the formation of piperazine is the result of relative instability of the intermediate 2-phenyl-1-triflylaziridine, because its analog, 2-phenyl-1-tosylaziridine is stable [30].Presumably, the stability of aziridine 10 is due to the presence of the second phenyl group stabilizing the molecule.In methylene chloride, the NIS-induced reaction also gives aziridine 10 in about the same yield, but with NBS it is the minor product, whereas the major product was identified to be N-(2-bromo-1,2diphenylethyl)triflamide 11 (Scheme 6).
The structure and composition of imidazole 9 was confirmed by IR, NMR spectroscopy, and high-resolution mass spectrometry (HRMS), which showed the molecular ion [M + H] + with m/z 369.08807 corresponding to C17H16F3N2O2S + .When using NIS as the oxidant, imidazole 9 was also formed but as a minor product, the major one being 2,3-diphenyl-1-triflylaziridine 10 isolated in 78% yield (Scheme 5).The formation of aziridine 10 is the first case of the synthesis of N-sulfonylaziridines using N-sulfonylimino-λ 3 -iodanes as a source of the nitrogen group.The structure of aziridine 10 was proved by IR and NMR spectroscopy and confirmed by HRMS data.In particular, the values of the 1 JCH constants in the aziridine moiety are known to be much larger than in saturated aliphatic compounds and lie in the range of 170-180 Hz [32,33,34].The measured value of 1 JCH in product 10 is 177 Hz, which unambiguously proves its structure.The HRMS spectrum shows a molecular ion m/z at 328.06242, corresponding to the molecular formula C15H13F3NO2S + .
Earlier, it was shown that the reaction of styrenes with tosylamide in acetonitrile in the presence of t-BuOI leads to the substituted aziridines.[35] However, no aziridine is formed in the reaction with triflamide under the same conditions, but only the product of bis-triflamidation and disubstituted piperazine, which is, formally, the product of dimerization of the target aziridine [30].It can be assumed that the formation of piperazine is the result of relative instability of the intermediate 2-phenyl-1-triflylaziridine, because its analog, 2-phenyl-1-tosylaziridine is stable [30].Presumably, the stability of aziridine 10 is due to the presence of the second phenyl group stabilizing the molecule.In methylene chloride, the NIS-induced reaction also gives aziridine 10 in about the same yield, but with NBS it is the minor product, whereas the major product was identified to be N-(2-bromo-1,2-diphenylethyl)triflamide 11 (Scheme 6).The structure of the regioisomers was assigned based on the chemical shifts and multiplicity of the signals in the 1 H and 13 C NMR spectra.The NH signals in compounds 13 and 15 appear as clearly resolved doublets, whereas in their isomers 14 and 16, they look as an unresolved broad singlet (X = Br) or as a triplet (X = I).In regioisomers 13 and 15 the methine protons of the CH-CH 2 spin system resonate in a higher field than the methylene protons, whereas in regioisomers 14 and 16 their relative position is reversed.In the 13 C NMR spectra, the most upfield signals belong to the CH 2 Br (37 ppm) or CH 2 I carbons (13 ppm).
Replacing the solvent in the reaction in Scheme 7 from methylene chloride to acetonitrile gives rise to the formation of additional products.In the presence of NIS, apart from regioisomers 15 and 16, the isomeric amidines 17 and 18 were isolated as the products of solvent interception (Scheme 8): Scheme 7. Regioselectivity of halotriflamidation of styrene with N-triflylimino-λ 3 -iodane 1.
The structure of the regioisomers was assigned based on the chemical shifts and multiplicity of the signals in the 1 H and 13 C NMR spectra.The NH signals in compounds 13 and 15 appear as clearly resolved doublets, whereas in their isomers 14 and 16, they look as an unresolved broad singlet (X = Br) or as a triplet (X = I).In regioisomers 13 and 15 the methine protons of the CH-CH2 spin system resonate in a higher field than the methylene protons, whereas in regioisomers 14 and 16 their relative position is reversed.In the 13 C NMR spectra, the most upfield signals belong to the CH2Br (37 ppm) or CH2I carbons (13 ppm).
Replacing the solvent in the reaction in Scheme 7 from methylene chloride to acetonitrile gives rise to the formation of additional products.In the presence of NIS, apart from regioisomers 15 and 16, the isomeric amidines 17 and 18 were isolated as the products of solvent interception (Scheme 8): In a similar way the reaction proceeds in the presence of NBS, except for the formation of imidazoline 19 isomeric to the earlier synthesized 5-cyclohexyl-2-methyl-1-triflyl-4,5dihydro-1H-imidazole [27] and the product of solvent interception/hydrolysis 20 in the total yield of 88% (Scheme 9): Scheme 7. Regioselectivity of halotriflamidation of styrene with N-triflylimino-λ 3 -iodane 1.
The structure of the regioisomers was assigned based on the chemical shifts and multiplicity of the signals in the 1 H and 13 C NMR spectra.The NH signals in compounds 13 and 15 appear as clearly resolved doublets, whereas in their isomers 14 and 16, they look as an unresolved broad singlet (X = Br) or as a triplet (X = I).In regioisomers 13 and 15 the methine protons of the CH-CH2 spin system resonate in a higher field than the methylene protons, whereas in regioisomers 14 and 16 their relative position is reversed.In the 13 C NMR spectra, the most upfield signals belong to the CH2Br (37 ppm) or CH2I carbons (13 ppm).
Replacing the solvent in the reaction in Scheme 7 from methylene chloride to acetonitrile gives rise to the formation of additional products.In the presence of NIS, apart from regioisomers 15 and 16, the isomeric amidines 17 and 18 were isolated as the products of solvent interception (Scheme 8): The NMR and HRMS spectra for compounds 13-19 is offered in Supplementary Materials (Figures S21-S39, S43 and S44).
A mechanistic scheme allowing to explain the formation of all products in Schemes 2-9 is presented in Scheme 10.The specific reactivity of triflamide leads to the formation (under the conditions of the reactions) of both N-sulfonylamidines, products containing acetamide and triflamide groups, and products formed without the participation of a solvent as a reagent in the reaction.Since the basicity of acetonitrile (780 kJ/mol) [36] is higher than that of triflamide (740 kJ/mol) [1], acetonitrile is a stronger nucleophile than triflamide, which leads to the formation of amidines (or the corresponding acetamides upon hydrolysis of the corresponding intermediate), as shown in Scheme 10.The use of CH 2 Cl 2 eliminates the involvement of the solvent in the reaction.
triflamide, which leads to the formation of amidines (or the corresponding acetamides upon hydrolysis of the corresponding intermediate), as shown in Scheme 10.The use of CH2Cl2 eliminates the involvement of the solvent in the reaction.
Scheme 10 is consistent with the formation of N-triflylaziridine 10 (instead of the corresponding amidine) for the best nucleofuge (X = I) even in MeCN, as well as with a much higher yield of 10 for X = I than for X = Br when performing the reaction in CH2Cl2 (Scheme 10): Scheme 10.A tentative mechanism for the formation of diverse products in the oxidative sulfonamidation of alkenes.

General Details
The 1 H (400.1 MHz), 13 C (100.6 MHz), and 19 F (376.0 MHz) NMR spectra were registered on a Bruker DPX-400 spectrometer for 5-10% solutions in CDCl3. 1 H and 13 C chemical shifts (δ) are reported in parts per million (ppm) relative to the residual solvent peak of CDCl3 (δ = 7.27 ( 1 H) and 77.10 ( 13 C) ppm, respectively). 19F NMR chemical shifts (δ) are given relative to CCl3F.All coupling constants (J) are reported in hertz (Hz).Abbreviations are s, singlet; d, doublet; t, triplet; q, quartet; and brs, broad singlet.The IR spectra (cm −1 ) were taken on a Bruker Vertex 70 spectrometer.Mass spectra were registered in ESI-TOF-HRMS mode on an Agilent 6210 instrument (Agilent Technologies, Santa Clara, CA, USA).Elemental composition was determined on a Thermo Scientific Flash 2000 CHNS analyzer.Melting points were measured on a Boetius apparatus.TLC was performed on silica 60 plates (0.25 mm, F254, Merck, Rahway, NJ, USA) and visualized by UV lamp.Commercial reagents and solvents were used without further purification unless otherwise mentioned.Scheme 10 is consistent with the formation of N-triflylaziridine 10 (instead of the corresponding amidine) for the best nucleofuge (X = I) even in MeCN, as well as with a much higher yield of 10 for X = I than for X = Br when performing the reaction in CH 2 Cl 2 (Scheme 10):

General Details
The 1 H (400.1 MHz), 13 C (100.6 MHz), and 19 F (376.0 MHz) NMR spectra were registered on a Bruker DPX-400 spectrometer for 5-10% solutions in CDCl 3 . 1H and 13 C chemical shifts (δ) are reported in parts per million (ppm) relative to the residual solvent peak of CDCl 3 (δ = 7.27 ( 1 H) and 77.10 ( 13 C) ppm, respectively). 19F NMR chemical shifts (δ) are given relative to CCl 3 F.All coupling constants (J) are reported in hertz (Hz).Abbreviations are s, singlet; d, doublet; t, triplet; q, quartet; and brs, broad singlet.The IR spectra (cm −1 ) were taken on a Bruker Vertex 70 spectrometer.Mass spectra were registered in ESI-TOF-HRMS mode on an Agilent 6210 instrument (Agilent Technologies, Santa Clara, CA, USA).Elemental composition was determined on a Thermo Scientific Flash 2000 CHNS analyzer.Melting points were measured on a Boetius apparatus.TLC was performed on silica 60 plates (0.25 mm, F254, Merck, Rahway, NJ, USA) and visualized by UV lamp.Commercial reagents and solvents were used without further purification unless otherwise mentioned.

Synthesis of Phenyl-N-triflylimino-λ 3 -iodane 1
Triflamide (0.50 g, 3.4 mmol) was added to a solution of iodosolbenzene (0.75 g, 3.4 mmol) in methylene chloride (10 mL) and stirred for 5 min.Then, the solvent was distilled off to dryness in a vacuum, and the solid white residue was washed with hexane to remove triflamide.The residue was dried in a vacuum to obtain 1.10 g (94%) iminoiodane 1.

Scheme 3 .
Scheme 3. Bromotriflamidation of styrene with solvent interception in the presence of NBS.The structure of amidine 6 was confirmed by the presence of the NH doublet at 7.67 ppm, a doublet of triplets of CHN at 5.34 ppm, two doublets of diastereotopic CH2Br at 3.73 and 3.64 ppm, and the Me group singlet at 2.48 ppm.The 13 C NMR spectrum contains the signals at 169 (C=N), 58 (CHN), 34 (CH2Br), and 22.3 (Me).The NMR spectra for compounds 3, 4, 6 is offered in Supplementary Materials (FiguresS1-S9).In the presence of NIS, styrene reacts with N-triflylimino-λ 3 -iodane 1 in acetonitrile to give the product of bis-triflamidation TfNHCH(Ph)-CH2NHTf 7 in 54% yield, identical to that obtained earlier by the reaction with triflamide in the system t-BuOCl/NaI[30].In continuation, we examined the reaction of compound 1 with some alkenes in the system I2/NaI/MeCN, which was successfully employed for the synthesis of N-tosylaziridines[31] (vide supra).In contrast, no aziridine was formed with compound 1, but only the aforementioned adduct 7 in a low yield of 25%.Under the same conditions, trans-stilbene and vinylcyclohexane did not react with compound 1.UV activation did not change the course of the reaction and only increased the yield of adduct 7 to 40%.When the oxidant I2/NaI was replaced by NBS or NIS, the reaction of N-triflylimino-λ 3 -iodane 1 and trans-stilbene 8 in acetonitrile led to cyclization and formation of 2-methyl-4,5-diphenyl-1-triflyl-4,5-dihydro-1H-imidazole 9 (Scheme 4).

Scheme 3 .
Scheme 3. Bromotriflamidation of styrene with solvent interception in the presence of NBS.The structure of amidine 6 was confirmed by the presence of the NH doublet at 7.67 ppm, a doublet of triplets of CHN at 5.34 ppm, two doublets of diastereotopic CH 2 Br at 3.73 and 3.64 ppm, and the Me group singlet at 2.48 ppm.The 13 C NMR spectrum contains the signals at 169 (C=N), 58 (CHN), 34 (CH 2 Br), and 22.3 (Me).The NMR spectra for compounds 3, 4, 6 is offered in Supplementary Materials (FiguresS1-S9).In the presence of NIS, styrene reacts with N-triflylimino-λ 3 -iodane 1 in acetonitrile to give the product of bis-triflamidation TfNHCH(Ph)-CH 2 NHTf 7 in 54% yield, identical to that obtained earlier by the reaction with triflamide in the system t-BuOCl/NaI[30].In continuation, we examined the reaction of compound 1 with some alkenes in the system I 2 /NaI/MeCN, which was successfully employed for the synthesis of Ntosylaziridines[31] (vide supra).In contrast, no aziridine was formed with compound 1, but only the aforementioned adduct 7 in a low yield of 25%.Under the same conditions, trans-stilbene and vinylcyclohexane did not react with compound 1.UV activation did not change the course of the reaction and only increased the yield of adduct 7 to 40%.When the oxidant I 2 /NaI was replaced by NBS or NIS, the reaction of N-triflyliminoλ 3 -iodane 1 and trans-stilbene 8 in acetonitrile led to cyclization and formation of 2-methyl-4,5-diphenyl-1-triflyl-4,5-dihydro-1H-imidazole 9 (Scheme 4).

Scheme 2 .
Scheme 2. Oxidative triflamidation/iodination of styrene with compound 1 in the presence of N-halosuccinimides in methylene chloride.The structure of the products and, hence, the regioselectivity of addition is proved by the presence of the NH signal at 5.76 (3) and 5.89 ppm (4), multiplets of the methine proton at 4.97 (3) and 4.78 ppm (4), and doublets of doublets at 3.74 (3) and 3.56 (4) of the methylene protons.Varying the solvent from CH2Cl2 to MeCN changes the course of the reaction; with NBS, N-(2-bromo-1-phenylethyl)-N'-(triflyl)acetimidamide 6 is obtained in moderate yield (Scheme 3).

Scheme 3 .
Scheme 3. Bromotriflamidation of styrene with solvent interception in the presence of NBS.The structure of amidine 6 was confirmed by the presence of the NH doublet at 7.67 ppm, a doublet of triplets of CHN at 5.34 ppm, two doublets of diastereotopic CH2Br at 3.73 and 3.64 ppm, and the Me group singlet at 2.48 ppm.The 13 C NMR spectrum contains the signals at 169 (C=N), 58 (CHN), 34 (CH2Br), and 22.3 (Me).The NMR spectra for compounds 3, 4, 6 is offered in Supplementary Materials (FiguresS1-S9).In the presence of NIS, styrene reacts with N-triflylimino-λ 3 -iodane 1 in acetonitrile to give the product of bis-triflamidation TfNHCH(Ph)-CH2NHTf 7 in 54% yield, identical to that obtained earlier by the reaction with triflamide in the system t-BuOCl/NaI[30].In continuation, we examined the reaction of compound 1 with some alkenes in the system I2/NaI/MeCN, which was successfully employed for the synthesis of N-tosylaziridines[31] (vide supra).In contrast, no aziridine was formed with compound 1, but only the aforementioned adduct 7 in a low yield of 25%.Under the same conditions, trans-stilbene and vinylcyclohexane did not react with compound 1.UV activation did not change the course of the reaction and only increased the yield of adduct 7 to 40%.When the oxidant I2/NaI was replaced by NBS or NIS, the reaction of N-triflylimino-λ 3 -iodane 1 and trans-stilbene 8 in acetonitrile led to cyclization and formation of 2-methyl-4,5-diphenyl-1-triflyl-4,5-dihydro-1H-imidazole 9 (Scheme 4).

Scheme 6 .Scheme 5 .
Scheme 6. Aziridination and bromotriflamidation of stilbene with N-triflylimino-λ 3 -iodane 1.According to the NMR spectroscopy data, compound 11, possessing two chiral carbon atoms, is formed as a mixture of two pairs of diastereomers.Two sets of the NH, CHBr, and CHN signals and two pairs of the CHBr and CHN 13 C signals appear in the ratio of 5:1.The NMR and HRMS spectra for compounds 9-11 is offered in Supplementary Materials (Figures S10-S20 and S40-S42).The reaction of vinylcyclohexane 12 with N-triflylimino-λ 3 -iodane 1 in methylene chloride in the presence of NBS or NIS results in a mixture of the regioisomers of the products of bromo-or iodotriflamidation in the ratio of 1:2 (13:14 = 21:41%) or 1:3 (15:16 = 14:43%) and total yield of 62 or 57% (Scheme 7):

3. 2 . 1 .
Scheme 10.A tentative mechanism for the formation of diverse products in the oxidative sulfonamidation of alkenes.