Copper-catalyzed direct decarboxylative fluorosulfonylation of aliphatic carboxylic acids.

Sulfonyl fluorides are emerging as key structural motifs in organic synthesis, medicinal chemistry, and materials science. Herein we report two efficient and complementary methods for direct decarboxylative fluorosulfonylation of carboxylic acids by the merging of copper catalysis with different N-centered HAT regents. A wide range of structurally diverse sulfonyl fluorides was readily accessed from primary, secondary, and tertiary carboxylic acids in a single step under mild conditions.

Catalytic Decarboxylative Fluorosulfonylation Enabled by Energy-Transfer-Mediated Photocatalysis.

Sulfonyl fluorides are useful building blocks in a wide array of fields. Herein, we report a catalytic decarboxylative fluorosulfonylation approach for converting abundant aliphatic carboxylic acids to the corresponding sulfonyl fluorides. This transformation is enabled by simple preactivation as aldoxime esters and energy-transfer-mediated photocatalysis. This operationally simple method proceeds with high functional-group tolerance under mild and redox-neutral conditions.

Photoredox-catalyzed aminofluorosulfonylation of unactivated olefins.

The development of efficient approaches to access sulfonyl fluorides is of great significance because of the widespread applications of these structural motifs in many areas, among which the emerging sulfur(vi) fluoride exchange (SuFEx) click chemistry is the most prominent. Here, we report the first three-component aminofluorosulfonylation of unactivated olefins by merging photoredox-catalyzed proton-coupled electron transfer (PCET) activation with radical relay processes. Various aliphatic sulfonyl fluorides featuring a privileged 5-membered heterocyclic core have been efficiently afforded under mild conditions with good functional group tolerance. The synthetic potential of the sulfonyl fluoride products has been examined by diverse transformations including SuFEx reactions and transition metal-catalyzed cross-coupling reactions. Mechanistic studies demonstrate that amidyl radicals, alkyl radicals and sulfonyl radicals are involved in this difunctionalization transformation.

Organocatalytic enantioselective SN1-type dehydrative nucleophilic substitution: access to bis(indolyl)methanes bearing quaternary carbon stereocenters.

A highly general and straightforward approach to access chiral bis(indolyl)methanes (BIMs) bearing quaternary stereocenters has been realized via enantioconvergent dehydrative nucleophilic substitution. A broad range of 3,3'-, 3,2'- and 3,1'-BIMs were obtained under mild conditions with excellent efficiency and enantioselectivity (80 examples, up to 98% yield and >99 : 1 er). By utilizing racemic 3-indolyl tertiary alcohols as precursors of alkyl electrophiles and indoles as C-H nucleophiles, this organocatalytic strategy avoids pre-activation of substrates and produces water as the only by-product. Mechanistic studies suggest a formal SN1-type pathway enabled by chiral phosphoric acid catalysis. The practicability of the obtained enantioenriched BIMs was further demonstrated by versatile transformation and high antimicrobial activities (3al, MIC: 1 µg mL-1).