Enantioselective Cyanoalkenylation And Borylacylation Of Styrenes Catalyzed By Copper

The enantioselective difunctionalization of styrenes has always attracted much attention from chemists because two functional groups can be constructed in olefins simultaneously.In the field of organic synthesis,the asymmetric difunctionalization of styrenes catalyzed by copper catalyst has got remarkable development.As we all know,copper is a kind of non-precious metal that has many advantages,such as low toxicity,low price and abundant reserves.Based on previous studies,we explored new catalytic systems which provide more synthetic methods for the synthesis of organic structural uints.This thesis mainly focuses on copper-catalyzed enantioselective cyanoalkenylation and borylacylation of styrenes.In the first chapter of this paper,application of NHPI esters in recent years,copper-catalyzed asymmetric free radical reaction and copper-catalyzed asymmetric cyanation and boration were reviewed.The second chapter and the third chapter respectively focus on cyanoalkenylation and borylacylation of styrenes.The specific contents are as follows:1.Asymmetric cyanoalkenylation of styrenes catalyzed by copper and photoredoxWe developed a copper and photoredox catalyzed method for enantioselective cyanoalkenylation of styrenes using trimethylcyanosilane(TMSCN)and N-hydroxyphthalimide esters(NHPI esters)which is widely used as a kind of radical precursor in organic synthesis.The photoredox catalyst induced alkenyl radical adds to styrene,then generate key benzylic radical which couples with Cu~Ⅱ and chiral ligand.Subsequently,the intermediate proceeds through reductive elimination to give the final cyanoalkenylation product,via release of Cu~Ⅰ.This radical cyanation reaction features satisfactory safety,broad substrate scope,low cost,availability of raw materials and high yields and enantioselectivities.This reaction has good practicability because the product can be further functionalized,which represents a new method of cyanation and alkenylation of styrenes.2.Asymmetric borylacylation of styrenes catalyzed by copperWe developed a copper catalyzed method for enantioselective borylacylation of styrenes with good yields and enantioselectivities using bis-(pinacolato)diboron as boration reagent and acyl chloride as acylation reagent.This reaction only need 30 min at room temperature to complete and only need 2 mol% Cu-ligand.Both styrenes and indene derivatives,both benzoyl chloride and alkyl acid chloride are efficient substrates for the borylacylation reaction.The β-borylated ketone products are versatile intermadiates in organic chemistry and can undergo further transformations to obtain useful various chiral ketone compounds.