Unlocking the Potential of β-Fragmentation of Aminophosphoranyl Radicals for Sulfonyl Radical Reactions

Abstract

Exploiting β-scission in aminophosphoranyl radicals for radicalmediated transformations has been a longstanding challenge. In this study, we investigated the untapped potential of β-fragmentation in aminophosphoranyl radicals by leveraging the unique properties of the P−N bond and the substituents of P(III) reagents. Our approach carefully considers factors such as cone angle and electronic properties of phosphine and employs density functional theory (DFT) calculations to probe structural and molecular orbital influence. We successfully induced β-fragmentation through N−S bond cleavage of aminophosphoranyl radicals under visible light and mild conditions, generating a range of sulfonyl radicals derived from pyridinium salts via the photochemical activity of electron donor−acceptor (EDA) complexes. This innovative synthetic strategy exhibits broad applicability, including late-stage functionalization, and paves the way for valuable sulfonyl radicalmediated reactions, such as alkene hydrosulfonylation, difunctionalization, and pyridylic C−H sulfonylation.

Oxidant-Assisted Sulfonylation/Cyclization Cascade Synthesis of Alkylsulfonylated Oxindoles via the Insertion of SO2

“…Due to the importance of this sulfonyl group, the synthesis of sulfones has attracted continuous interest and a number of synthetic methods have been reported in recent years . At present, the sulfone derivatives were generally prepared from the oxidation of sulfides, the functionalization of sulfinates, or the addition of sulfonyl radicals to unsaturated C–C bonds. − Particularly, numerous efforts have been dedicated to developing efficient methods for the preparation of sulfone-containing molecules through a radical strategy by employing arylsulfinic acids, aryl sodium sulfonate, sulfonyl hydrazides, and sulfonyl chlorides as sulfonyl radical precursors. Although significant progress has been achieved in this field, there are some problems retained, such as requiring high reaction temperature, employing hazardous reagents, or needing strong oxidants, which would limit the further application of these avenues.…”

Light-promoted photocatalyst-free and redox-neutral hydrosulfonylation of unactivated alkenes using sulfinic acid

“…While the existing approaches can furnish alkyl-substituted sulfones conveniently, either photocatalysts or tailor-made substrates that enable single electron transfer (SET) 20 or an electron donor-acceptor (EDA) complex 22 are typically required. In addition, these reported studies are not ideal in terms of atom economy.…”

DBU‐Promoted [3+2] Cyclization/Retro‐Mannich Cascade Reaction of N‐Aminoisoquinolinium and N‐Aminoquinolinium Derivatives with para‐Quinone Methides

“…(a) As nitrogen-centered radical precursors and pyridine surrogates, they participate in radical-based functionalization, with cleavage of the NÀ N bond in the reaction. Pioneering work in the field has been reported by Hong, [2] Power, [3] and so on. [4] 2) As 1,3-dipoles, they participate in a number of annulations, affording various heterocyclic compounds via [3 + 2] and [3 + 3] reaction modes.…”