Visible‐Light‐Induced Photoredox 1,1‐Dichloromethylation of Alkenes with Chloroform

Abstract

A photoredox 1,1‐dichloromethylation of alkenes with the readily available bulk chemical chloroform was described, furnishing a variety of 1,1‐dichloroalkane products selectively. Furthermore, this transformation could proceed smoothly on gram‐scale, and the obtained products could transform into diverse γ‐lactam derivatives with simple treatment. Mechanistically, the single electron transfer (SET) with excited photocatalyst and subsequent deprotonation of triethylamine generates the key α‐aminoradical intermediate, which enables selective Cl‐atom transfer of chloroform. The specific selectivity, broad substrate scope, as well as the mild reaction conditions make this strategy especially attractive.

Rapid Access to γ,γ‐Dichloroketones via Radical‐Induced Dichloromethylation and Concomitant 1,2‐Aryl Migration of Allylic Alcohols with CHCl3

“…We simply applied the optimal reaction conditions established by our previous research on radical‐mediated multi‐component reactions of olefins (Table 1). [15c,16] Oxidants screening shows that TBHP was the best oxidant while other oxidants afforded the product 3 a in much lower yields (entries 1–4). As the next optimization step, we investigated the amount of TBHP, reducing or increasing the usage of TBHP could not increase the yield of 3 a (entries 5–8).…”

Photoinduced activation of alkyl chlorides

“…In 2022, the Huang group 41 reported a photoinduced radical addition of electron-deficient alkenes with chloroform, preparing a series of structurally diverse 1,1-dichloromethyl derivatives in moderate to excellent yields (Scheme 16). Interestingly, the obtained products can be further converted into different heterocyclic compounds.…”

Aminals as powerful XAT-reagents: activation of fluorinated alkyl chlorides

“…These a-aminoalkyl radicals effectively activate alkyl iodides 23,24 and uorinated bromides, 25 while reactions with chlorides are rare. 26 We proposed that switching from amines to aminals may provide more effective XAT reagents due to the additional donor effect of the second nitrogen on the radical center. Herein, we report that 1,3,5-triazinane N1 exhibits very high reactivity in XAT processes owing to its cyclic structure.…”