Reviving the Coordination Chemistry of Sulfonium Cations

ABSTRACT: More than a century old, sulfonium ions are still intriguing species in the landscape of organic chemistry. On one hand they have found broad applications in organic synthesis and material science, but on the other hand, while isoelectronic to the ubiquitous tertiary phosphine ligands, their own coordination chemistry has been neglected for the last three decades. Here we report the synthesis and full characterization of the first Rh(I) and Pt(II) complexes of sul-fonium. Moreover, for the first time, the coordinating ability of an aromatic sulfonium has been established. A thorough computational analysis of the exceptionally short S-Rh bonds obtained attests for the strongly π-accepting nature of sul-fonium cations and places them among the best π-acceptor ligands available today. Our calculations also show that when embedded within a pincer framework their π-acidity is enhanced. Therefore, in addition to the stability and modularity that these frameworks offer, our pincer complexes might open the way for sulfonium cations to become powerful tools in π-acid catalysis.

Sulfonium Ion-Promoted Traceless Schmidt Reaction of Alkyl Azides

Schmidt reaction by sulfonium ions is described. General primary, secondary, and tertiary alkyl azides were converted to the corresponding carbonyl or imine compounds without any trace of the activators. This bond scission reaction showcased ring-opening, -expansion, and one-pot further conversion of the substrates as well as the application with C-H azidation.

Sulfonium Ion-Promoted Traceless Schmidt Reaction of Alkyl Azides

Schmidt reaction by sulfonium ions is described. General primary, secondary, and tertiary alkyl azides were converted to the corresponding carbonyl or imine compounds without any trace of the activators. This bond scission reaction showcased ring-opening, -expansion, and one-pot further conversion of the substrates as well as the application with C-H azidation.

Sulfonium Ion-Promoted Traceless Schmidt Reaction of Alkyl Azides

Schmidt reaction by sulfonium ions is described. General primary, secondary, and tertiary alkyl azides were converted to the corresponding carbonyl or imine compounds without any trace of the activators. This bond scission reaction showcased ring-opening, -expansion, and one-pot further conversion of the substrates as well as the application with C-H azidation.

Sulfonium Ion-Promoted Traceless Schmidt Reaction of Alkyl Azides

Schmidt reaction by sulfonium ions is described. General primary, secondary, and tertiary alkyl azides were converted to the corresponding carbonyl or imine compounds without any trace of the activators. This...

Chemoselective α-Sulfidation of Amides Using Sulfoxide Reagents

The direct α-sulfidation of tertiary amides using sulfoxide reagents under electrophilic amide activation conditions is described. Employing readily available reagents, selective functionalization takes place to generate isolable sulfonium ions en route to α-sulfide amides. Mechanistic studies support the critical role of activated sulfoxides that promote the desired transformation. For benzylic amide substrates, a single-step protocol featuring a spontaneous dealkylation step of a sulfonium ion intermediate was developed.

Chemoselective α-Sulfidation of Amides Using Sulfoxide Reagents

The direct α-sulfidation of tertiary amides using sulfoxide reagents under electrophilic amide activation conditions is described. Employing readily available reagents, selective functionalization takes place to generate isolable sulfonium ions en route to α-sulfide amides. Mechanistic studies support the critical role of activated sulfoxides that promote the desired transformation. For benzylic amide substrates, a single-step protocol featuring a spontaneous dealkylation step of a sulfonium ion intermediate was developed.