Nickel-catalyzed Selective Hydrocyanation Of C=C Double Bonds And Cyanation Of Allylic Alcohols

Transition-metal-catalyzed hydrocyanation of C=C double bonds and allylic cyanation reactions are green and efficient methods for the synthesis of alkyl nitrile compounds.Of note,the regulation of regioselectivity and stereoselectivity is a formidable challenge thereof.In this dissertation,the effective control of regio-and stereoselectivity and diverse synthesis in the catalytic formation of organonitriles were achieved by developing new and efficient catalytic systems,designing selective control strategies and tandem reactions.The main work of this dissertation includes the following three parts:Part I: The asymmetric hydrocyanation of racemic allenes with axial chirality was achieved for the first time by using the Ni(0)/bidentate phosphine ligand catalytic system.The reaction proceeds smoothly under mild conditions,which give rise to a wide array of chiral allyl nitrile compounds with excellent regio-and enantioselectivity.In addition,mechanistic studies suggest that regioselective migratory insertions may play the key role in delivering high enantioselectivity for the reaction.Part II: Using the Ni(0)/bidentate phosphite combination as the auto-tandem catalytic system,the tandemized cyanation/asymmetric hydrocyanation of dienyl allyl alcohols was realized to form chiral1,5-dinitrile compounds.This method features the following significant advantages:(1)The first direct use of allyl alcohol as a substrate for transition metal-catalyzed allylic cyanation;(2)The reaction has a broad substrate scope,high yield and enantioselectivity.The mechanism of tandem allylic cyanation and hydrocyanation of C=C double bond was confirmed through controlled experiments.Both experiments and theoretical calculations indicate that the hydrogen-nickel-cyano species probably participate in the cyanation of allyl alcohols through a transmetallation mechanism.Part III: A regiodivergent cyanation of allyl alcohols and cyanation/(isomerization)hydrocyanation tandem reaction were developed by using Ni(0)/bidentate phosphite ligand catalytic system.These reactions are characterized by the following merits:(1)Quaternary carbon centers containing cyano groups can be constructed through branch-selective allylic cyanation reaction;(2)A series of dinitriles with different chain lengths were synthesized with high regioselectivity and excellent yields through the tandem regiodivergent cyanation/(isomerization)hydrocyanation of allyl alcohols.Furthermore,the key roles of ligand configurations and substituents in regulating the regioselectivity of allylic cyanation reactions were disclosed through theoretical calculations.