Visible‐Light‐Induced Vicinal Dichlorination of Alkenes through LMCT Excitation of CuCl₂

Abstract

This work demonstrates photoredox vicinal dichlorination of alkenes, based on the homolysis of CuCl2 in response to irradiation with visible light. This catalysis proceeds via a ligand to metal charge transfer process and provides an exciting opportunity for the synthesis of 1,2‐dichloride compounds using an inexpensive, low‐molecular‐weight chlorine source. This new process exhibits a wide substrate scope, excellent functional group tolerance, extraordinarily mild conditions and does not require external ligands. Mechanistic studies show that the ready formation of chlorine atom radicals is responsible for the facile formation of C−Cl bonds in this synthetic process.

Visible‐Light‐Induced Homolysis of Earth‐Abundant Metal‐Substrate Complexes: A Complementary Activation Strategy in Photoredox Catalysis

“…Capitalizing on Kochi's discovery, Wan and co‐workers developed a visible‐light‐induced vicinal dichlorination of olefins by directly using CuCl 2 as a photoactive species without any exogenous ligand [Scheme 1 D, Eq. a‐ii] [16] . Although a combination of 20 mol % CuCl 2 and 2.5 equiv hydrochloric acid as the chlorine source was required for effective dichlorination of unactivated olefins, 4.0 equiv CuCl 2 alone were adequate to induce the same transformations for activated olefins upon irradiation with a 38W white LED ( λ =390–760 nm).…”

Recent Advances in Visible-Light-Promoted Copper Catalysis in Organic Reactions

“…38 It is worth noting that, in those reactions, the copper catalysis In 2020, on the basis of Kochi's discovery 39 , a visible-lightinduced vicinal dichlorination of alkenes through excitation of CuCl2 has been reported by Wan group (Scheme 20). 40 According to the proposed catalytic cycle (Figure 8), the excited CuCl2 proceeds via a ligand to metal charge transfer (LMCT)…”

“…In 2020, on the basis of Kochi's discovery, 39 a visiblelight-induced vicinal dichlorination of alkenes through excitation of CuCl 2 was reported by the Wan group (Scheme 20). 40 According to the proposed catalytic cycle (Figure 9), the excited CuCl 2 proceeds via a ligand-to-metal charge transfer (LMCT) process and provides an exciting chance for the synthesis of 1,2-dichloro compounds using an inexpensive and commercially available chlorine source.…”

Durch sichtbares Licht induzierte Homolyse unedler, gut verfügbarer Metallsubstratkomplexe: Eine komplementäre Aktivierungsstrategie in der Photoredoxkatalyse

“…a-ii]). [16] Während eine Kombination von 20 Mol-% CuCl 2 und 2.5 ¾quivalenten (equiv) Salzsäure als Chlorquelle füre ine wirksame Dichlorierung von nicht aktivierten Olefinen erforderlich war, waren 4.0 equiv CuCl 2 allein ausreichend, um die gleichen Tr ansformationen füra ktivierte Olefine bei Bestrahlung mit einer weißen 38-W-LED (l = 390-760 nm) zu induzieren. In jüngster Zeit hat die Rovis-Gruppe die selektive C(sp 3 )-H-Alkylierung und -Aminierung von gut verfügbaren Alkanen mit elektronenarmen Olefinen wie Acrylaten und Vinylsulfonen in Gegenwart von katalytischem CuCl 2 unter langwelliger UV-Bestrahlung erreicht.…”