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

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

A novel radical 1,4/5-amino shift from the oxygen center of alkene-tethered diphenyl ketoxime ethers to the carbon center to achieve high value-added fluoroalkyl-containing primary β(γ)-amino-ketones is reported. Mechanism studies reveal that the migration is triggered by the alkene addition of fluoroalkyl radical derived from the electron donor-acceptor (EDA) complex of Togni's reagent II or fluoroalkyl iodides and quinuclidine, and involves a unique 5(6)-exo-trig cyclization of the carbon-centered radical onto the N-atom of ketoxime ethers followed by a cascade sequence of N-O bond cleavage and dehydrogenation. Notably, besides Togni's reagent II and fluoroalkyl iodides, this protocol is also compatible with other radical precursors to provide various functionalized primary aminoketones.

Acridinium Salts and Cyanoarenes as Powerful Photocatalysts: Opportunities in Organic Synthesis

The use of organic photocatalysts has revolutionized the field of photoredox catalysis, as it allows access to reactivities that were traditionally restricted to transition-metal photocatalysts. This Minireview reports recent developments in the use of acridinium ions and cyanoarene derivatives in organic synthesis. The activation of inert chemical bonds as well as the late-stage functionalization of biorelevant molecules are discussed, with a special focus on their mechanistic aspects.

Truce-Smiles Rearrangements by Strain Release: Harnessing Primary Alkyl Radicals for Metal-Free Arylation

The ring-opening of 3-aminocyclobutanone oximes enables easy generation of primary alkyl radicals, capable of undergoing an unprecedented strain-release, desulfonylative radical Truce-Smiles rearrangement, providing divergent access to valuable 1,3 diamines and unnatural β-amino acids. Characterized by mild conditions and wide scope of migrating species, this protocol allows the modular assembly of sp³ -aryls under transition metal-free, room-temperature conditions.

Triarylmethanes and their Medium-Ring Analogues by Unactivated Truce-Smiles Rearrangement of Benzanilides

Intramolecular nucleophilic aromatic substitution (Truce–Smiles rearrangement) of the anions of 2‐benzyl benzanilides leads to triarylmethanes in an operationally simple manner. The reaction succeeds even without electronic activation of the ring that plays the role of electrophile in the S_NAr reaction, being accelerated instead by the preferred conformation imposed by the tertiary amide tether. The amide substituent of the product may be removed or transformed into alternative functional groups. A ring‐expanding variant (n to n+4) of the reaction provided a route to doubly benzo‐fused medium ring lactams of 10 or 11 members. Hammett analysis returned a ρ value consistent with the operation of a partially concerted reaction mechanism.

Functionalization of α-C(sp3 )-H Bonds in Amides Using Radical Translocating Arylating Groups

α-C-H arylation of N-alkylamides using 2-iodoarylsulfonyl radical translocating arylating (RTA) groups is reported. The method allows the construction of α-quaternary carbon centers in amides. Various mono- and disubstituted RTA-groups are applied to the arylation of primary, secondary, and tertiary α-C(sp3 )-H-bonds. These radical transformations proceed in good to excellent yields and the cascades comprise a 1,6-hydrogen atom transfer, followed by a 1,4-aryl migration with subsequent SO2 extrusion.

Boron-doped TiO2 (B-TiO2): visible-light photocatalytic difunctionalization of alkenes and alkynes

Boron-doped TiO₂ (B-TiO₂) was prepared, characterized, and applied as a reusable, inexpensive, and available heterogeneous nanophotocatalyst under visible light for the synthesis of phenacyl thiocyanates.