Transition Metal-catalyzed Reductive Carbonylation

Transition metal catalyzed carbonylation has undergone tremendous advances since the1940s.Currently,carbonylation has become one of the most valuable methods for the synthesis of carbonyl containing compounds.In addition,the resulting carbonyl group is a useful structural synthon that can be readily convert into many other functional groups.According to the change of the oxidation state of the reaction raw materials and products,the carbonylation reaction can be divided into three types,reductive carbonylation,oxidative carbonylation and neutral carbonylation reaction.Neutral carbonylation reactions have been reported many with cross-coupling carbonylation reactions,while reports of reduction carbonylation and oxidative carbonylation are relatively rare.As a C1 source of the traditional carbonylation reaction,CO gas has the advantages of low cost,easy availability,and high atomic economy,so it is often used in industrial production.However,the toxicity and uncontrollability of CO gas have led to less research in experiments.Therefore,numerous efforts have been made to develop new CO-free carbonylation procedures and a series of novel carbonylation reactions can be developed.In recent years,my research group has been engaged in research on the development of CO-free carbonylation and the design of new carbonylation reactions.Based on our previous work,I have conducted in-depth research on formic acid as C1,hydrogen source and hydroxyl source.We have developed formylation reaction,carboxylation reaction and carbonylative aminohomologation under the palladium catalysis.At the same time,a nickel-catalyzed carbonylative homologation of aryl iodides was developed.This paper mainly introduces the following work:1.In-depth study of C1,hydrogen source and hydroxyl source of formic acid,and under the condition of palladium catalysis,the advantages of ligand regulation can be used to efficiently prepare aldehyde and carboxylated products directly from halogenated aromatic hydrocarbons.Under the control of single and double-dentate ligands,two products can be obtained with high selectivity,and at the same time,it has wide substrate suitability.2.Using formic acid as the source of C1 and hydroxyl,and using the allyl derivative as the starting material,the butenoic acid derivative is directly obtained under the catalytic conditions of palladium metal.The reaction conditions are simple and there is a moderate to good yield on the substrate.3.Using CO gas as the C1 source,using excess formic acid as the reducing agent,the halogenated aromatic hydrocarbon can be directly selected to obtain the aminomethyl compound or benzylformamide under the palladium catalysis.We call this kind of reaction carbonylative aminohomologation.The reaction has a wide range of substrate applicability,mild reaction conditions,different products can be controlled by different solvents,and has a greater promoting effect on the carbonylation reaction.4.After the completion of the aminohomologation,the research on the homologation is further studied.Using nickel as a catalyst,Mo?CO?₆ as a carbonyl source and silane as a reducing agent,an carbonylative homologation of indole?or aromatic ring?and aryl iodide has been developed.In the reaction,the carbonylation reaction can be carried out at both the C2 and C3 positions of the indole,and a wide range of benzyl hydrazine derivatives are synthesized in moderate to excellent yields,and various types of aromatic rings having electron donating can be applied to the reaction..