Synthesis of N -arylsulfonylimidazolidine-4-ones from N -(2,2,2-trichloroethylidene)arenesulfonamides and monochloroacetamide

The reaction of N-(2,2,2-trichloroethylidene)arenesulfonamides with monochloroacetamide involves nucleophilic addition to the C=N bond of the imine function, to give N-(arenesulfonamido-2,2,2-trichloroethyl)chloroacetamides. The latter, in the presence of bases, undergo intramolecular cyclization to give imidazole derivatives


Introduction
We have reported that the products of the reaction of N-(2,2,2-trichloroethylidene)arenesulfonamides with ethylenechlorohydrin, 1 ethylene glycol, mercaptoethanol 2 as well as hydroxyacetic and mercaptoacetic 3 acids were successfully used in the synthesis of heterocyclic compounds of the oxazole-and thiazole series.The addition reactions of the amides of halocarboxylic acids with N-functionally substituted imines of polyhaloaldehydes should result in products which would be promising for the synthesis of heterocyclic compounds, but have not been studied yet, although the interaction of many amides with N-functionally substituted imines of polyhaloaldehydes have been studied in detail. 4Investigation of the reactions of chloral arenesulfonylimines with monochloroacetamide seems to be important because it should give route for synthesizing new heterocyclic derivatives of N-arylsulfonyl-substituted imidazoles.

Chemistry
It was found that N-(2,2,2-trichloroethylidene)arenesulfonamides reacted with the amide of monochloroacetic acid amide to give the products of nucleophilic addition to the C=N bond.As expected, chloroacetamide shows lower reactivity in its reactions with chloral arenesulfonylimines than do the other amides of carboxylic acids which have been studied in similar processes. 4This can be explained by the electron-accepting effect of the halogen atom.We have defined conditions for the reaction, which result in good yields of the addition products 1−3 (Scheme 1).

Scheme 1
The behavior of the synthesized diamides 1−3 under conditions leading to their cyclization involving NH and CH 2 Cl groups has been studied.
It was found that the diamides 1−3, under the influence of aqueous or alcoholic alkalis, underwent an intramolecular cyclization to give the imidazolidine-4-one derivatives 4−6.Alcohol and alkali promoted a side process of substitution of the chlorine atom in the chloroacetamide fragment by an alkoxy group, and the compound 7 was formed (Scheme 2).

Scheme 2
The compounds 1−6 were colorless crystalline products, soluble in acetone and DMSO and insoluble in aliphatic hydrocarbons and water.

NMR and IR data
The structure of the diamides 1−3 was confirmed by spectroscopic data (Tables 1−3).In the 1 H NMR spectra, proton signals of both the substituted aromatic ring and of the -NH-CH-NH-fragment were observed.The latter fragment presented as low-field doublets of the NH group and a triplet of the СНgroup.The non-equivalent protons of the СН 2 Cl fragment appeared as an AB-system.In the 13 С-NMR spectra of diamides 1-3, the signals were assigned to the carbonyl group, aromatic ring, CCl 3 , СН 2 Cl and СН groups.The protons of the 1H NMR spectra of the cyclic compounds 4−6 appeared as broad singlets of the NH group at low field, signals of the aromatic ring, and a singlet for the methane proton (Table 1).Unlike the acyclic products 1−3, splitting of the methane proton signal by the NHproton was not observed, which could be explained by the presence of the enol form of imidazolidones 4−6 in the solution.The non-equivalent protons of the methylene group were appeared as dd.In the 13 С NMR spectra of the compounds 4, 5 (Table 2) signals of the carbon atom of carbonyl group, aromatic rings, ССl 3 group, and СН and СН 2 fragments were presented.The signals were slightly shifted towards high field in comparison with the same signals of the acyclic products 1−3.
The compound 7 was isolated as a mixture with the compound 5; however, its structure was unambiguously confirmed by 1 H NMR data.In the spectra of the precipitate prepared by treatment of diamide 2 with alcoholic alkali, proton signals corresponding to the cyclic derivative 5 were present, but the triplet and quartet could be assigned to the ethoxy group as well as the proton signals of the aromatic rings and multiplets of NH, СН and СН 2 -groups, whose shifts differed from the shifts of diamide 2 and compound 5 (Table 1).
As Table 3 illustrates, the IR spectra of the compounds 1−3 and 4−6 confirmed their structures.The low values of νNH, νС=О, as well as their doublet form, could be explained by both intramolecular-(compounds 1−3) and intermolecular hydrogen bonding in the crystalline state.The carbonyl absorption bands of the cyclic products 4−6 were shifted to high frequency, in accord with ref. 5, so the vibration frequencies were increased while the valence angles decreased in systems such as С-СО-С when 5-membered cycles were formed.The formation of cyclic products 4−6 was also confirmed by the presence of νSO 2 high-frequency bands, (especially for asymmetric vibration), which could be assigned to the inductive effect of the 5membered N-containing heterocycles. 6,7A series of absorption bands of 5-membered cycle skeleton in the 1350−1005 cm -1 region, which was not observed in spectra of acyclic compounds, 8 was indicative of the formation of the saturated heterocycles 4−6.Absorption bands of the СОNH "Amide II" fragment in the 1520−1540 cm -1 region are typical for acyclic Nsubstituted amides, while these vibration bands in 5-membered lactams were shifted to lower frequency.Indeed, these bands for the compounds 4−6 were observed in the 1430−1440 cm -1 region.We intend to study further the stereochemical properties, electronic structure, types of hydrogen bonds, donor-acceptor interactions of the compounds obtained, and analyze the comparative characteristics of cyclic and acyclic compounds.

Addition of chloroacetamide to trichloroethylidenearenesulfonamides
A solution of N-(2,2,2-trichloroethylidene)arenesulfonamides (0.01 mol) was prepared by the reaction of N,N-dichloroarenesulfonamides and trichloroethylene. 1 Chloroacetamide (0.93 g, 0.01 mol) was added to the solution and the mixture was heated at reflux for 5 h under an inert gas flow.After cooling, the precipitate was filtered off, to give products 1−3.

Table 3 .
Infrared spectral data (cm -1 ) for the main groups in compounds 1−6 in KBr