Copper-Catalyzed Regiodivergent Alkylboration Reactions Of Unactivated Alkenes And Alkynes

As the most basic unit of the organism,the construction of carbon-carbon bonds has always been the core proposition in organic synthesis.In recent years,transition-metal-catalysis has been evolved into a powerful tool for building carbon-carbon bonds.In these reactions,transition-metals are used to catalyze the cross-coupling of organic electrophiles and organic nucleophiles to build carbon-carbon bonds.Organic electrophilic reagents are usually organic halides,sulfonates of alcohols or phenols,organic diazo compounds,and etc.;but organic nucleophiles are usually the air-sensitive organometallic reagents.Recently,the carboboration of copper-catalyzed unsaturated bonds provides a new strategy for the construction of carbon-carbon bonds.This strategy not only uses the abundant and readily alkenes and alkynes instead of organometallic reagents as substrates,but also introduces the boron group which can continue to derivatized in the construction of carbon-carbon bonds at the same time.In the first chapter,we reviewed the copper-catalyzed boration bifunctional reactions of unsaturated bonds.Except the introduction of carboboration of unsaturated bonds,we also summarized the relevant aminoboration,oxyboration and borylstannylation of unsaturated bonds.As an important synthetic fragment in organic synthesis,alkenes have the advantages of abundant accessibility,low price and stable nature.The construction of C(sp3)-C bonds by carboboration of alkenes is an attractive strategy.However,in the previous work,the substrate range of the alkene is limited to activated alkenes such as styrenes and acrylates,and the reaction of the most common alkyl substituted alkene has not been studied in depth due to its low activity and hardly controlled regioselectivity.In the second chapter,we explored the alkylboration of unactivated alkenes.In this reaction,we sloved the slow rate of the addition of CuB intermediates to unactivated alkenes by the strategy of corrodination-promoting addition.More importantly,we achieved a regiodivergent carboboration reaction by the fine-tuning of the ligand structure.This reaction provides a general and efficient strategy for the construction of saturated carbon-carbon bonds from abundant and readily alkenes.Relative to the aryl metal reagents,the source of alkenyl metal reagents is very limited.The alkenyl C(sp2)-C bond can be directly formed by the alkenyl copper intermediate produced by the addition of copperboron intermediates,thus avoiding the preparation of the alkenyl metal reagent.Moreover,the boron unit can be easily converted into various functional groups.In the third chapter,we successfully achieved regiodivergent carboboration of unactivated terminal alkynes by the use of nitrogen/phosphine ligand pairs.With simple conversion,we can selectively obtain the various bifunctional products of alkynes.This reaction provides an efficient method for the synthesis of trisubstituted olefin fragments that are widely present in natural products.In summury,we solve the problem that the low reactivities and hardly controlled regioselectivity of unactivited alkenes and alkynes which is not solved in the previous work,through the strategy of the corrodination-promoting addition and the regulation of the ligand in the reaction.The successful application of unactivated alkenes and alkynes has greatly expanded the application range of carboboration reaction,so that the constructed carbon-carbon bond has been extended from the specific sites such as benzyl and carbonyl a-site to the general unactivated sites.In addition,the Xantphos/Cy-Xantphos ligand pair and the dppbz/DMAP ligand pair provide effective ligand pairs for the copper-catalyzed bifunctional boration reaction of alkenes and alkynes,respectively,which is instructive for the subsequent study in this field.However,some problems still exist,such as the control of entioselectivity in the addition of alkenes,the reactivity of the secondary alkyl electrophilic reagents is very low and so on.We will solve these problems in the following study.