Bis-β-sulfanylethylester and cyclic disulfide-S-oxides as precursors of bifunctionalized anionic derivatives with two oxidized sulfurs

The cyclic disulfide and the bis-β-sulfanyl ethyl ester derived from dithiol, N,N′-1,2-phenylenebis(3-methyl-3-sulfanylbutanamide) were used as precursors to prepare upon oxidation the cyclic disulfide-S-oxides and the thioether sulfur oxidized species including thioether/sulfoxide, bis-sulfoxide, sulfoxide/sulfone, and bis-sulfone. Ring cleavage with KOH/EtOH of the cyclic disulfide-S-monooxide followed by reaction of the opened intermediate with ethyl acrylate afforded the sulfinate/β-sulfanyl ethyl ester derivative. Selective oxidation with 1 and 2 equiv of (3S)-3-tert-butyl-3-methyl-2-(phenylsulfonyl)oxaziridine or with 3 equiv of DMD led to the isolation of a series of compounds containing a sulfonate and a β-sulfanyl, a β-sulfinyl, and a β-sulfonyl ethyl ester. Retro-Michaël reaction applied to the β-sulfonyl/β-sulfinyl and bis-β-sulfonyl derivatives enabled to produce compounds containing a sulfinate and a β-sulfinyl or a β-sulfonyl ethyl ester as well as the bis-sulfinate dianion. DMD oxidation of the latter afforded the bis-sulfonate dianion. All these anionic species were characterized by 1H NMR, mass spectrometry, HRMS or elemental analysis. Sulfenates in such pseudopeptidic structures could not be isolated from the ring cleavage of the cyclic disulfide-S-dioxide or from a retro-Michaël reaction applied to the β-sulfinyl ethyl ester. A cyclization reaction leading to an isothiazolidin-3-one is likely to occur as observed from the ring cleavage of the cyclic disulfide-S-dioxide. Finally, Ni(II) and Co(III) have been inserted into the disulfinate dianion leading to the corresponding diamidato/disulfinato complexes S-bonded to Ni(II) or Co(III) centers.