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

The cyclic disulfide and the bis-beta-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/beta-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 beta-sulfanyl, a beta-sulfinyl, and a beta-sulfonyl ethyl ester. Retro-Michael reaction applied to the beta-sulfonyl/beta-sulfinyl and bis-beta-sulfonyl derivatives enabled to produce compounds containing a sulfinate and a beta-sulfinyl or a beta-sulfonyl ethyl ester as well as the his-sulfinate dianion. DMD oxidation of the latter afforded the bis-sulfonate dianion. All these anionic species were characterized by H-1 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-Michael reaction applied to the beta-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. (C) 2008 Elsevier Ltd. All rights reserved.