SO₂ conversion to sulfones: development and mechanistic insights of a sulfonylative Hiyama cross-coupling

Abstract

A Pd-catalyzed Hiyama cross-coupling reaction using SO2 is described.

Flow Electrosynthesis of Sulfoxides, Sulfones, and Sulfoximines without Supporting Electrolytes

“…13 C­{ 1 H} NMR (126 MHz, CDCl 3 ) δ 138.4, 133.9, 129.2, 128.7, 124.9, 124.8, 61.0 ppm. The spectroscopic data agree with the literature …”

“…The spectroscopic data agree with the literature. 61 Sulfonyldibenzene (3v). Compound 3v was synthesized following GP2 using diphenylsulfane (1v, 279 mg, 1.5 mmol) to give the product as a white solid.…”

Sequential C–S and S–N Coupling Approach to Sulfonamides

“…It has been reported that Au-, , Cu-, and Pd-catalyzed , reactions of arylboronic acids and SO 2 surrogate lead to sulfinate salts. Recently, similar activation of organosilanes to generate sulfinates under metal-free conditions has been reported . We found that the three-component reaction between phenylboronic acids, K 2 S 2 O 5 , and CH 3 I gave PhSO 2 Me in 25% yield under heavy-metal-free conditions.…”

A copper(I)-catalyzed sulfonylative Hiyama cross-coupling

“…In presence of one equivalent of fluoride anions, a fluoride copper species is likely to be formed (A→C, ΔG = -3.2 kcal•mol −1 ) to then proceed to the transmetalation with the organosilane. 25 Although it has already been reported and experimentally evidenced that a stable FSO2 − anion is formed from DABSO and fluoride anions, 7,26 this adduct can also serve as a fluoride transfer agent to generate a copper(I) fluoride complex. As regards the transmetalation between the silane and the Cu-F species, computational results show a more favored transition state when the fluoride anion is in axial position on the silicon center (C→D, ΔG ≠ (TS2) = 19.2 kcal•mol −1 vs ΔG ≠ (TS2 ' ) = 24.9 kcal•mol −1 for the equatorial position, see ESI).…”

“…6 Recently, we described the first Pd-catalyzed sulfonylative Hiyama cross-coupling with sp 2 -hybridized electrophiles. 7 Surprisingly, only allylsilanes were found to react with sulfur dioxide, arylsilanes being inert under the reaction conditions. A careful mechanistic study unveiled that the organosilane was not involved in a transmetalation step, but instead reacting through a SE2' mechanism, restricting the scope to the formation of allyl aryl sulfones.…”