Photocatalyic Transformations Of Alkyl Bromides

In recent years,visible light photoredox catalysis has been widely used in organic synthesis because it features environmental benign,efficient and mild.However,reports on photocatalytic transformations of haloalkanes,especially the cheap and readily available?-carbonyl alkyl bromides,are rare.Moreover,these methods are often performed under harsh conditions and exists some potential danger,with most of which relied on transition-metal catalysts?e.g.,Cu,Fe,Ni?and oxidants in a stoichiometric amount.Thus,the development of mild,environmental benign visible light photoredox catalysis for the transformations of?-carbonyl alkyl bromides is highly desired.This paper mainly studies the transformations of?-carbonyl alkyl bromides using visible light photoredox catalysis,which includes the following contents:?1?Recent progress in both visible light-catalyzed difunctionalization of olefins and the reactions with?-carbonyl alkyl bromide are described detailedly.The visible light catalyzed functionalization of olefins according to their utilizations in the construction of different bonds.By comparing with the common thermochemical reaction,the advantages and disadvantages of the visible light photoredox catalysis for the?-carbonyl bromide functionalization reaction or coupling reaction are also summarized.?2?Cooperative metal photocatalyst[Ru?ppy?₃Cl₂]and copper catalyze 1,2-arylalkylation of olefins with?-carbonyl alkyl bromides and N,N-disubstituted anilines is developed.This reaction allows the construction of two new C-C bonds at room temperature,and this method can be applied to the introduction of various functional groups in moderate to high yields.This reaction provides a mild and practical method to produce diversified 1,1-diarylation products.?3?Visible light-catalyzed coupling reaction of imidazo[1,2-a]pyridines with?-carbonyl alkyl bromides is presented.This reaction is applicable to various primary,secondary and tertiary?-carbonyl alkyl bromides.In the presence of photocatalyst and base,the reaction works well with various substituents on the phenyl or pyridine ring,giving the desired products in in moderate to good yields.