Photocatalytic Difunctionalization of Vinyl Ureas by Radical Addition Polar Truce–Smiles Rearrangement Cascades

Abstract

We report tandem alkyl‐arylations and phosphonyl‐arylations of vinyl ureas by way of a photocatalytic radical‐polar crossover mechanism. Addition of photoredox‐generated radicals to the alkene forms a new C−C or C−P bond and generates a product radical adjacent to the urea function. Reductive termination of the photocatalytic cycle generates an anion that undergoes a polar Truce–Smiles rearrangement, forming a C−C bond. The reaction is successful with a range of α‐fluorinated alkyl sodium sulfinate salts and diarylphosphine oxides as radical precursors, and the conformationally accelerated Truce–Smiles rearrangement is not restricted by the electronic nature of the migrating aromatic ring. Formally the reaction constitutes an α,β‐difuctionalisation of a carbon–carbon double bond, and proceeds under mild conditions with visible light and a readily available organic photocatalyst. The products are α,α‐diaryl alkylureas typically functionalized with F or P substituents that may be readily converted into α,α‐diaryl alkylamines.

Recyclable ZnIn2S4 Microspheres for Photocatalytic Azolation of N-Heterocycles

“…It is interesting to note that the sequence of the corresponding (112)/(102) intensity ratios of the synthesized ZnIn 2 S 4 samples was as follows: ZIS-1 > ZIS-2 > ZIS-3 (see Table S1 and Figure S2). Generally, a larger ratio indicates more exposed facets, 64 which might enhance the interaction of ZnIn 2 S 4 with organic substrates in catalytic processes. 65,66 The UV−vis diffuse reflectance spectra of the as-synthesized ZnIn 2 S 4 are shown in Figure 2b.…”

Radical 1,4/5‐Amino Shift Enables Access to Fluoroalkyl‐Containing Primary β(γ)‐Aminoketones under Metal‐Free Conditions

“…Radical migration reactions especially long-range shifts provide ap owerful means for molecular reconstruction by affording functional groups (FGs) at the distal position which cannot be easily introduced by other ways. [1] By using the structurally specific alcohols or Smiles rearrangement models, radical 1,4/5-migration of alkenyl, [2] carbonyl, [3] alkynyl, [4] cyano, [5] and (hetero)aryl [6] has been realized and widely applied in organic synthesis (Scheme 1a,left). Although great success has been achieved in long-range migration of Ccentered FGs,such structural constraints of migration models limit their application in the radical shift of heteroatomcentered FGs, [7] so,itisimperative to develop new migration models.…”

Strategies for the Photocatalytic Generation of Carbanion Equivalents for Reductant-Free C–C Bond Formations

“…As mentioned above, the strategy was recently exploited for a photocatalytic S N Ar reaction as well, showcasing the broad applicability of photocatalitically generated carbanion intermediates ( Figure 4 B). 24 Mostly sulfinates ( 2 ) were again used as radical precursor for the addition to vinyl ureas ( 6 ). After radical reduction, the corresponding carbanion ( IX ) is arylated via a Truce–Smiles rearrangement.…”