Reduction of N-(polychloroethylidene)- and N-(1-hydroxypolychloroethyl) arenesulfonamides with adamantane in the presence of superacids

Abstract

N-(2,2,2-Trichloroethylidene)-, N-(2,2-dichloro-2-phenylethylidene)-, and N-(1-hydroxy-2-polychloroethyl)arenesulfonamides reacted with adamantane in carbon tetrachloride in the presence of oleum or concd. H 2 SO 4 -P 4 O 10 mixture to give the corresponding N-(2-polychloroethyl)arenesulfonamides as a result of reduc-tion of the azomethine and OH group, respectively. N-Arylsulfonyl-substituted polychlorinated aldehyde imines possess an activated CH=N bond and are convenient building blocks for the preparation of various acyclic and cyclic sulfonamide derivatives [1, 2]. We previously developed efficient preparative procedures for the synthesis of N-(2,2,2-trichloroethylidene)-and N-(2,2-dichloro-2-phenylethylidene)arenesulfonamides I and II via radical reactions of N,N-dichloroarenesulfonamides with trichloroethylene and phenylacetylene [1][2][3][4], so that these important reagents became accessible. We perform systematic studies on reactions of polyhalogenated aldehyde imines in the presence of strong acids. For instance, oleum as superacid [5] is capable of protonating electron-deficient azomethine group in N-sulfonyl imines to generate amidoalkyl carbocations. Among possible further transformations of the latter, C-amidoalkylation of aromatic and heteroaromatic compounds was studied most thoroughly [6][7][8][9].In the present work we examined transformations of imines Ia, Ib, IIa, and IIb in the presence of superacids and found that these compounds are capable of reacting with adamantane to give products of reduction of the CH=N group, the corresponding N-(polychloroethyl)arenesulfonamides III and IV (Scheme 1). The reactions successfully occurred in the presence of oleum or a mixture of concentrated sulfuric acid with phosphoric anhydride; however, no reduction occurred in the presence of H 2 SO 4 , P 4 O 10 , or phosphoric acid taken separately. N-(Polychloroethyl)arenesulfonamides IIIa, IIIb, IVa, and IVb were also obtained from N-(1-hydroxy-2-polychloroethyl)arenesulfonamides Va, Vb, VIa, and VIb under analogous conditions (in the presence of adamantane and oleum or H 2 SO 4 -P 4 O 10 mixture).It is known that in the presence of acids adamantane can formally act as hydride ion donor in reactions with cycloalkenes, alcohols, and ketones [10,11]. However, analogous behavior of adamantane toward Schiff bases was not reported previously. According to [12], hydride transfer reactions of carbonyl compounds with branched hydrocarbons in the presence of superacids are possible only with dicationic intermediates possessing superelectrophilic properties, but no such reactions occur with monocations. By analogy, we presumed that protonation of Schiff bases Ia, Ib, IIa, and IIb gives superelectrophilic dications A. Protonation of hemiaminals Va, Vb, VIa, and VIb is accompanied by elimination of water, leading to the same dicationic species. The driving force for the subsequent formation of N-polychloroethyl sulfonamides IIIa, IIIb, IVa, and IVb via reaction of dications A with adamantanes is likely to be formation of...

Gamma-irradiation produces active chlorine species (ACS) in physiological solutions: Secoisolariciresinol diglucoside (SDG) scavenges ACS - A novel mechanism of DNA radioprotection

“…Instead, we found a new signal at 3.77 ppm. According to the literature, this chemical shift corresponds to the signal of methylene β-protons in a Ph(Ar)-CCl 2 -CH 2 -N structural fragment [49] (Fig. 2A and B).…”

MeOH‐Mediated Efficient Reduction with N‐Heterocyclic Carbene Boranes Towards the Synthesis of Cyclic Sulfamates and Sulfonamides

“…[4] Among the different methods, the reduction of cyclic Nsulfonylimines is one of the most common approaches accessing these compounds. [5] In this context, in 2005, Rueping and coworkers [6] mentioned Hantzsch dihydropyridine could be used as a hydrogen source in the presence of diphenyl phosphate (Scheme 1a). In 2021, Kamal's group [7] reported a much simpler process, in which the imines could be effectively reduced by using 0.75 to 1.50 equivalent of Me 2 S-BH 3 in a methanol solvent at 60 °C (Scheme 1b).…”