Thianthrene 5‐Oxide as a Mechanistic Probe in Oxygen Transfer Reactions: The Case of Carbonyl Oxides versus Dioxiranes Revisited

Abstract

Thianthrene 5-oxide (SSO) constitutes a useful mechanistic tool for the assessment of the electronic character of oxygen transfer agents by means of their X,, values, which reflect the extent of nucleophilic oxidation at the SO site in SSO. Treatment of dioxiranes 1 a-d with the SSO probe confirms that these are electrophilic oxidants (Xso < 0.15). Dioxirane sulfoxidation is sensitive to protic solvents and acids, which implies a polar mechanism (S,2) with nucleophilic attack of the sulfide electron pair on the dioxirane peroxide bond. In contrast, the carbonyl oxides 2a and b, diethyl persulfoxide (3), and adamantylideneadamantane perepoxide (4) are nucleophilic oxidants (Xso > 0.85). However, the cyclopentadienone carbonyl oxides 2c and d show low Xso values typical for electrophilic oxygen transfer agents. For these car-

Investigation of the Reaction Mechanism for the Epoxidation of Alkenes with Hydrogen Peroxide Catalyzed by a Protonated Tetranuclear Peroxotungstate with NMR Spectroscopy, Kinetics, and DFT Calculations

“…The oxidation products (SOSO = thianthrene 5,10‐dioxide, SSO 2 = thianthrene 5,5‐dioxide, and SOSO 2 = thianthrene 5,5,10‐trioxide) were analyzed quantitatively by HPLC: eluent, CH 3 OH/CH 3 CN/H 2 O = 60:15:25; flow rate 0.4 mL min –1 , column temperature 303 K, detection at λ = 254 nm. The reaction conditions (e.g., concentrations of substrate, substrate/oxidant ratios, and reaction temperatures) were controlled to minimize overoxidation to SOSO 2 and then to estimate the true electronic nature of the oxidant 30. The X SO value was calculated according to the following equation reported:30 X SO = (nucleophilic oxidation)/(total oxidation) = (SSO 2 + SOSO 2 )/(SSO 2 + SOSO + 2SOSO 2 ).…”

Comparative Study of Metal‐Catalyzed Iminations of Sulfoxides and Sulfides

“…Moreover, formation of the trans ‐sulfilimine 12 was clearly favored, especially under silver‐catalyzed conditions. This observation was not surprising, considering the reported importance of steric and electronic effects on both the rate and the site of further oxidation of thianthrene‐5‐oxide depending on the oxidation conditions employed 20f,h…”

Dioxirane Oxidation of Sulfur‐Containing Organic Compounds

“…They proved that the formation of sulfone 4 cannot take place via the DMD oxidation of the sulfinyl oxygen of thianthrene 5-oxide (3) (Scheme 3). Later, Adam et al [32][33][34] reinvestigated the dioxirane oxidation of the thianthrene 5-oxide (3). The careful analysis of all the reaction products unequivocally proved that both dimethyldioxirane (1) and methyl(trifluoromethyl)dioxirane (2) are strongly electrophilic oxidants.…”