Photocatalytic Barbier reaction – visible-light induced allylation and benzylation of aldehydes and ketones

Abstract

We report a photocatalytic version of the Barbier type reaction using readily available allyl or benzyl bromides and aromatic aldehydes or ketones as starting materials to generate allylic or benzylic alcohols.

Emerging Organic Photoredox Catalysts for Organic Transformations

“…E ox * , E ox 0 , energy level of T 1 , and triplet quantum yield) which are comparable to those of Ir(ppy) 3 , as well as remarkably longer‐living T 1 (480 ± 50 µs vs. 1.9 µs) catalyzed the organic transformation of small molecules such as photoredox/Ni dual‐catalyzed C–N cross‐coupling reactions of amines and C–S cross‐coupling reactions of thiols with aryl bromides . König and co‐workers reported 68 ‐catalyzed photocatalytic Barbier‐type reaction of allyl or benzyl bromides with aromatic aldehydes or ketones to generate allylic or benzylic alcohols via a reductive radical‐radical cross‐coupling . Aldehydes underwent single‐electron reduction by 68 in the excited state in the presence of N,N ‐diisopropylethylamine (DIPEA) and LiBF 4 , followed by coupling with allyl or benzyl radical produced by DIPEA and light irradiation.…”

Photoredox Catalysis of Aromatic β‐Ketoesters for in Situ Production of Transient and Persistent Radicals for Organic Transformation

“…(4)]. Interestingly, when benzophenone, [18] a well-known hydrogen and electron acceptor was added under the standard conditions, another ketyl radical suppressed the formation of ketyl radical A, leading to pinacolcoupling products 9 b and 9 b' in 64 % combined yield as well as the benzannulation product 8-1 in 72 % yield [Eq. (5)].…”

Redox Neutral and Acid-Free Minisci C-H Alkylation of Heteroarenes Enabled by Dual Photoredox/bromide Catalysis in Micellar Solutions

“…Fluorescence Quenching 4,5 For fluorescence quenching experiments, a 50 µM solution of the Ir(dtbbpy)(ppy)2PF6 in degassed water/SDS solution was prepared under nitrogen atmosphere in a gas-tight 10 mm quartz cuvette. The photocatalyst solution was irradiated with 410 nm and the fluorescence emission upon addition of potential quenchers was recorded.…”