Phosphine/Photoredox Catalyzed anti-Markovnikov Hydroamination of Olefins with Primary Sulfonamides via a-Scission from Phosphoranyl Radicals

New strategies to access radicals from common feedstock chemicals hold the potential to broadly impact synthetic chemistry. We report a dual phosphine and photoredox catalytic system that enables direct formation of sulfonamidyl radicals from primary sulfonamides. The method is proposed to proceed via -scission of the sulfonamidyl radical from a phosphoranyl radical intermediate, generated upon sulfonamide nucleophilic addition to a phosphine radical cation. As compared to the recently well-explored β-scission chemistry of phosphoranyl radicals, this strategy is applicable to activation of N-based nucleophiles and is catalytic in phosphine. We highlight application of this activation strategy to an intermolecular anti-Markovnikov hydroamination of unactivated olefins with primary sulfonamides. A range of structurally diverse secondary sulfonamides can be prepared in good to excellent yields under mild conditions.

Recent advances in phosphoranyl radical-mediated deoxygenative functionalisation

Alcohols and carboxylic acids have been established as versatile building blocks in the assembly of various carbon frameworks.

Homolytic Substitution at Phosphorus: An Ab initio Study of the Reaction of Hydrogen Atom and Methyl Radical With Phosphine and Methylphosphine

Homolytic substitution reactions of hydrogen atom and methyl radical at the phosphorus atom in phosphine and methylphosphine have been examined by high-level ab initio molecular orbital theory. MP4SDTQ/6-31G**//MP2(FC)/6-31G** calculations predict that free-radical attack at the phosphorus atom in phosphines is facile, with energy barriers of 14-33 kJ mol-1 and likely to involve hypervalent phosphoranyl radical intermediates. These intermediates, in turn, are found to have dissociative energy barriers of 10-31 kJ mol-1, depending on leaving group, and are unlikely to undergo pseudorotation prior to dissociation. MP5/6-31G**//MP2/6-31G** calculations indicate that permutational isomerism of phosphoranyl radical is likely to involve barriers of 145 and 127 kJ mol-1 for mechanisms involving transition states of D4h and C4v symmetry respectively.