Regioselective and oxidant-free sulfinylation of indoles and pyrroles with sulfinamides

Direct Bis-Alkyl Thiolation for Indoles with Sulfinothioates under Pummerer-Type Conditions

A base-free bis-alkyl thiolation reaction of indoles with sulfinothioates under Pummerer-type conditions is described. Sulfinothioates, activated with 2,2,2-trifluoroacetic anhydride, are demonstrated to be an efficient thiolation reagent for wide applications. This approach enabled double C-H thiolation at the C2 and C3 of the indole in one pot. The mechanism studies suggested the thiolation was realized through the sulfoxonium salt rather than sulfenyl carboxylate.

Direct conversion of sulfinamides to thiosulfonates without the use of additional redox agents under metal-free conditions

Direct conversion of sulfinamides to thiosulfonates is described. Without the use of additional redox agents, the reaction proceeds smoothly in the presence of TFA under metal-free conditions. This protocol possesses many advantages such as odourless and stable starting materials, broad substrate scope, selective synthesis, and mild reaction conditions.

Syntheses and Transformations of Sulfinamides

Sulfinamides, especially enantiopure sulfinamides, are widely used in organic and medicinal synthesis. Syntheses and transformations of racemic and enantioenriched sulfinamides have achieved great progress. Especially sulfinamides demonstrate interesting and valuable reactivity, which deserves to be pertinent. This review summarizes the latest development in the synthesis and transformation of sulfinamides and will be helpful for future related research.

1 Introduction

2 Synthesis of Sulfinamides

2.1 Synthesis of Racemic Sulfinamides

2.2 Synthesis of Enantiomerically Pure Sulfinamides

2.3 Synthesis of Other Sulfinamides

3 Transformations of Sulfinamides

3.1 Condensation with Aldehydes and Ketones

3.2 Reaction with Alkynes

3.3 Reaction with Alkenes

3.4 Reaction with Aryl and Alkyl Halides

3.5 Reaction with Alcohols, Dibenzyl Ether, and Benzyl Mercaptan

3.6 Synthesis of tert-Butyldisulfanyl-Substituted Hetarenes

3.7 Synthesis of Asymmetric Sulfides

3.8 Synthesis of N-Phosphino-sulfinamide Ligands

3.9 Asymmetric Synthesis of γ-Amino Acids

3.10 Sulfonylation of Heterocyclic Compounds

4 Summary and Outlook

Switchable regioselection of C–H thiolation of indoles using different TMS counterions

Simply swapping the counteranions of TMS leads to a switchable regioselectivity in C2– and C3–H thiolation of indoles.