Visible‐Light‐Induced Diradical‐Mediatedipso‐Cyclization towards Double Dearomative [2+2]‐Cycloaddition or Smiles‐Type Rearrangement

Abstract

When mono‐radical ipso‐cyclization of aryl sulfonamides tend to undergo Smiles‐type rearrangement through aromatization‐driven C−S bond cleavage, diradical‐mediated cyclization must perform in a distinct reaction pathway. It is interesting meanwhile challenging to tune the rate of C−S bond cleavage to achieve a chemically divergent reaction of (hetero) aryl sulfonamides in a visible‐light induced energy transfer (EnT) reaction pathway involving diradical species. Herein a chemically divergent reaction based on the designed indole‐tethered (hetero)arylsulfonamides is reported which involves a diradical‐mediated ipso‐cyclization and a controllable cleavage of an inherent C−S bond. The combined experimental and computational results have revealed that the cleavage of the C−S bond in these substrates can be controlled by tuning the heteroaryl moieties: a) If the (hetero)aryl is thienyl, furyl, phenanthryl, etc., the radical coupling of double dearomative diradicals (DDDR) precedes over C−S bond cleavage to afford cyclobutene fused indolines by double dearomative [2+2]‐cycloaddition; b) if the (hetero)aryl is phenyl, naphthyl, pyridyl, indolyl etc., the cleavage of C−S bond in DDDR is favored over radical coupling to afford biaryl products.

Triple-Dearomative Photocycloaddition: A Strategy to Construct Caged Molecular Frameworks

“…Compound 6 contains the dioxo-pentacycloundecane caged scaffold, which, to the best of our knowledge, has a single precedent in the literature from the work of West and co-workers as a minor product ( 7 , 5% yield) (Figure A). The reaction pathway from 3 and furan to 6 , an intermolecular triple-dearomative cycloaddition, is unprecedented in the literature.…”

Exploring novel aryl/heteroaryl-isosteres of phenylthiazole against multidrug-resistant bacteria

“…The residue was purified by flash chromatography (hexane : ethyl acetate = 4 : 1) to afford compounds 19–25 as white solids as reported. 33–35…”

Utilizing Visible Light to Enable Contra-Thermodynamic Skeletal Rearrangement for Dearomative meta-Cycloadditions of 2-Acetonaphthalenes via Triplet Energy Transfer Cascade

“…Recently, visible light-mediated triplet-triplet energy transfer ( VL EnT) catalysis has emerged as a powerful tool to initiate DACs (Figures 1a, b). 20,[39][40][41][42] The underlying concept is circumferent to achieving the excited triplet state population via EnT from an appropriate photosensitizer (PS) to the substrate. This approach leverages the enormous potential of excited state reactivity by employing mild visible light energy while ensuring the desired selectivity.…”