Unexpected reaction of N , N -dichloroarenesulfonamides with divinyl sulfide: formation of N -[2-chloro-and N -[2,2-dichloro-1-(arylsulfonylamino)ethyl]arenesulfonamides

Reaction of N , N -dichloroarenesulfonamides with divinyl sulfide was accompanied by cleavage of divinyl sulfide moiety and resulted in unexpected N -[2-chloro-and N -[2,2-dichloro-1-(arylsulfonylamino)ethyl]arenesulfonamides as final products. Possible reaction mechanism was discussed. The structure of bis(sulfonamido)chloroethanes synthesized was studied by X-ray analysis.


Introduction
N,N-Dichlorosulfonamides are important and available reagents in modern organic and elemento-organic synthesis.  A hh reactivity of N,N-dichlorosulfonamides is caused by the ability of N-Cl group to enter into a homolytic or heterolytic cleavage depending on conditions to produce sulfonylamidyl radicals and atomic chlorine, sulfonylamidyl anions and cations of chlorine or nitrenes.N,N-Dichlorosulfonamides, in contrast to N,N-dichloroacylamides or N,Ndichlorourethanes are more stable under keeping but at the same time are more selective and reactive 14,23 in reactions because of strong electro-withdrawing nature of sulfonyl group and weak conjugation between SO2 group and nitrogen atom.Due to such features N,Ndichlorosulfonamides are useful for diverse chemical transformations.][22] Divinyl sulfide is an important representative of practically useful sulfur organic compounds.The efficient method for the synthesis of divinyl sulfide was developed on the basis of acetylene and sodium sulfide, [28][29][30][31] which are available starting materials.9][30][31][32][33][34][35][36][37][38][39] The utilization of divinyl sulfide as cross-link monomer was used for the synthesis of new polymer products and ion exchange resins possessing unique properties. 29,30][31][32] Though divinyl sulfide was widely used in different reactions, [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] it was never studied in reaction with N,N-dichloroamides.Only oxidative imination and chlorination of 2,2dichlorovinyl sulfides by N,N-dichlorobenzensulfonamide are known. 40And in the present paper we studied the reaction of divinyl sulfide with N,N-dichloroarenesulfonamide 1a-c which are available typical representatives of N,N-dichlorosulfonamides.

Results and Discussion
It was expected that the reaction of divinyl sulfide with dichloroamides 1a-c can lead to products of chlorination, imination of sulfur atom or chloroamidation of double bonds, similar to the transformation of dichlorovinyl sulfide. 40Unexpectedly the process was found to result in the formation of N-[2-chloro-1-(arylsulfonylamino)ethyl]arenesulfonamides 2a-c and N-[2,2dichloro-1-(arylsulfonylamino)ethyl]arenesulfonamides 3a-c as the final compounds (Scheme 1).Yield of diamides 2a-c and 3a-c depended on both conditions and the order of the reagent mixing.
The influence of the reaction conditions was studied in detail with divinyl sulfide and dichloroamide 1b (Table 1).The reaction was carried out in CCl4 which does not react with dichloroamide 1b.The process was exothermic.A strong resinification was observed when the reagents were mixed without cooling and 4-chlorobenzensulfonamide was isolated as the only identified product in this case.The yield of bis-amides 2b, 3b was found to depend on both ratio and concentration of the reagents (Table 1).A dilution of the reaction mixture assisted to increasing of the yield of 2b to 69% when 4 equivalents of dichloroamide 1b were used (Table 1, Entry 8) and no compound 3b was produced under such conditions.At a higher concentration of the reagents bis-amide 3b was produced in the highest yield (30%) when 2 equivalents of dichloroamide 1b were added to cooled solution of divinyl sulfide (Table 1, Entry 6).When divinyl sulfide was added to a solution of dichloroamide 1b (Table 1, Entries 9, 10) diamides 2b, 3b were not obtained and complicated mixture of unidentified resin-like products of variable composition containing 21.45 -23.16% of sulfur and 28.93 -29.11% of chlorine was produced.
The bis-amides 2a-c are produced apparently via intermediates A and A1 which are formed after oxidative imination and chloroamidation of divinyl sulfide with dichloroamides 1a-c (Scheme 2).It may be suggested that intermediates A1 are subjected to further cleavage to produce vinylsulfenamides B and N-chloroenamides C. Such elimination of an unsaturated molecule is probably similar to reaction of sulfonium ylides containing a vinyl or ethinyl group. 41N-Chloroenamides C are able to be reduced into enamides D which turn into tautomers E followed by addition of 4-arenenesulfonamide to C=N group to give the final bis-amides 2a-c (Scheme 2).

Scheme 2. A possible mechanism for the formation of bis-amides 2a-c.
It is not inconceivable that bis-amides 3 are produced from intermediates A2 after imination and chlorination of divinyl sulfide (Schemes 2, 3).Taking into account the possibility of an olefin elimination from a vinyl containing sulfonium ylide system 41 it may be suggested that intermediates A2 are able to eliminate 1,2-dichloroethylene. 1,1-Bis(amido)-2,2-dichloroethanes are known to be formed in reaction of N,N-dichloroamides 1 with 1,2-dichloroethylene. 14,42 It was assumed that the reaction proceeded via saturated N-chloro-adducts F followed by easy dechlorination resulting in N-sulfonyldichloroacetaldimines G. 13 Then arenesulfonamides are added to intermediate imines G (Scheme 3).Nucleophilic addition of arenesulfonamides to haloaldimines has been previously reviewed in detail. 14robable vinylsulfenamides B produced both from intermediates A1 and A2 (Schemes 2, 3) obviously undergo further imination and chlorination accompanied by resinification of the reaction mass and formation of arenesulfonamides.
Reduction of the probable N-Cl intermediates and starting dichloroamides 1a-c into N-H derivatives is possible in reaction with different compounds containing C-H or N-H fragments which are present in the reaction mixture (Scheme 4).
Judging from the reaction course supported (Schemes 2-4), it is evident that increasing the ratio and concentration of dichloroamides 1a-c gives rise to increase probability of intermediates A1 formation (Scheme 2).Therefore yield of diamides 2a-c, produced from intermediates A1, is expected to be higher in this case.Under small ratio of dichloroamides 1a-c to divinyl sulfide probability of intermediates A1 formation decreases, yield of diamides 2a-c expected to be less, and in this case the second reaction course resulting in diamides 3a-c via intermediates A2 (Scheme 3) can be more significant.This conclusion is in accordance with experimental data shown in Table 1.In real situation yield of diamide 2b was much higher than yield of 3b when we used 4 equivalents of dichloroamide 1b (Table 1, Entries 3, 5, 8).The increased content of diamide 3b in the mixture of the products was found to be for the less quantity of dichloroamide 1b (Table 1, Entries 2, 4, 6, 7).Dilution of the reaction mixture led to increase in the yield of diamides 2b, 3b (Table 1, Entries 7, 8) probably because of less activity of side resinification process.Very large concentration and excess of dichloroamide 1b resulted in comprehensive resinification, and diamides 2b, 3b were not isolated at all as this took place when divinyl sulfide was added into excess of dichloroamide 1b (Entries 9, 10).
Other possible ways for the formation of the products are not ruled out.For instance, diamides 3a-c can be produced from the dichloroamides 1a-c and intermediates C (formed according to Scheme 3) via adducts H followed by reduction of N-Cl groups (Scheme 5).

Scheme 5. The possible formation of bis-amides 3a-c via enamides C and adducts H.
Unequivocal determination of the structures of diamides 2b, 3b was made by X-ray diffraction.The necessary single crystal samples were obtained by slowly evaporating solutions of 2b and 3b in the mixture of CH2Cl2 with n-heptane.It was found that the crystal structure of 2b is formed by two crystallographically independent molecules having different conformations.Molecules of every type are connected together through H-bonds (N-H…O(S), N…O 2.831(4)-2.975(4)Å) into the infinite bands.All other contacts are comparable in length to the sum of the van der Waals radii of corresponding atoms.H-bonds of the same type link molecules of 3b into framework (Figures 1, 2).

Conclusions
Thus, the first example of unusual reaction of N,N-dichlorosulfonamides with divinyl sulfide was demonstrated.Unexpected 1,1-bis(sulfonamido)-2-chloroethanes 2a-c and 1,1-bis(sulfonamido)-2,2-dichloroethanes 3a-c were obtained.The influence of conditions and ratio of the reagents on the reaction course and yield of diamides 2a-c, 3a-c was shown.The structure of diamides 2a-c, 3a-c was studied by spectral methods and X-ray analysis.The possible reaction way for the formation of compounds 2a-c and 3a-c was discussed.1,1-Bis(sulfonamido)-2-chloroethanes 3 are synthetically attractive as C-amidoalkylating reagents in reactions with aromatics and heteroaromatics. 43In addition, owing to NH and CH2Cl or CHCl2 groups in their structures, compounds 2a-c, 3a-c may be thought of as evident precursors of heterocyclic derivatives and ligands.

Experimental Section
General.N,N-Dichloro-arenesulfonamides 1a-c were obtained by chlorination of arenesulfonamides 15 and purified by recrystallization from CCl4.Divinyl sulfide was synthesized by the method. 28NMR spectra were recorded on a Bruker DPX 400 spectrometer ( 1 H, 400.13 MHz; 13 C, 100.61MHz) at 25 °C with HMDS as an internal standard.Chemical shifts are reported in ppm (δ), and coupling constants (J) in Hz.IR spectra were recorded on a Bruker IFS-25 spectrophotometer in KBr.All melting points were measured on a Kofler micro hot stage apparatus.Elemental analyses for C, H and N were obtained using a Thermo Finnigan Flash series1112 EA analyzer.Single crystal diffraction data for the compounds were collected on a SMART APEX II CCD (Bruker AXS) automatic diffractometer (Mo-Kα, λ = 0.71073 Å, T = 240 K); an absorption correction was applied using the Bruker SADABS program, version 2.10.The structures were solved by direct methods and refined by the full-matrix least-squares method in an anisotropic approximation for non-hydrogen atoms.The H atoms were calculated geometrically and used in riding model refinement.All structure solution and refinement calculations were carried out with SHELX-97 and Bruker SHELXTL Version 6.14 program packages.Crystallographic data (excluding structure factors) for the structures in this letter have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication numbers CCDC (2 -816999, 3 -817000).Copies of the data can be obtained, free of charge, on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [fax: +44(0)-1223-336033 or email: deposit@ccdc.cam.ac.uk].

Table 1 .
Yield of bis-amides 2b and 3b in the reaction of divinyl sulfide with dichloroamide 1b under various conditions a a The reaction mass was stirred at the appropriate temperature for 30 h to give a precipitate of the products.Resinification of the reaction mass and formation of 4-chlorobenzensulfonamide took place in any cases.b Solution of dichloroamide 1b in 20 mL CCl4 was added to solution of divinyl sulfide in 20 mL CCl4.c Solution of dichloroamide 1b in 50 mL CCl4 was added to solution of divinyl sulfide in 50 mL CCl4.d Solution of divinyl sulfide in 20 mL CCl4 was added to solution of dichloroamide 1b in 80 mL CCl4.