Asymmetric Functionalization Of Alkenes Catalyzed By Transition Metal

Alkenes are versatile compounds which are available on large scales in industry or through chemical synthesis.Substituted alkenes are outstanding prochiral compounds.And there is considerable interest among chemists in the development of methods for asymmetric functionalization of these compounds.Encouraging progresses in this field are constantly emerging.However,selective functionalization of alkenes,especially unactived alkenes,in a chemo-,regio-,diastereo-and enantioselective fashion is still well-known challenge in organic synthesis.This thesis describes several transition metals catalyzed asymmetric transformations of alkenes,including functionalization of 1,3-dienes,substrate-directed functionalization of unactivated alkenes and Aza-Heck type reaction.By using chiral palladium phosphate catalysis,we have established a one-pot highly selective multicomponent carbonyl allylation reaction of 1,3-butadienes,alkynyl bromides,and aldehydes with octaphenyl-2,2'-bi(1,3,2-dioxaborolane).The whole process proceeds via sequential reactions including oxidative addition,salt metathesis,insertion/?-allyl-Pd formation,asymmetric allylic borylation,and asymmetric carbonyl allylation.This process shows excellent generality for the reaction substrates and is able to deliver densely functionalized homoallylic alcohols in high levels of structural diversity and stereoselectivity.Chiral 3,4-dihydro-2H-1,4-benzoxazines are privileged structural moieties that are prevalent in natural products,drugs,and bioactive compounds.A palladium-catalyzed regioselective asymmetric aminohydroxylation reaction of 1,3-dienes with N-tosyl-2-aminophenols employing commercial chiral pyridinebis-(oxazoline)ligand has been successfully developed.The reaction proceeds through a cascade process consisting of an aminopalladation and a subsequent asymmetric intramolecular allylation.A variety of optically active 3,4-dihydro-2H-1,4-benzoxazines can be synthesized in high yields and enantioselectivities from readily available starting materials.We have developed a Pd(?)/amine cooperatively catalyzed highly enantioselective addition of cyclic ketones to unactivated alkenes cataining amide directed group.The Pd(?)enables the unactivated alkenes to be reactive enough toward the chiral enamine catalytically generated from enlizable ketones and the organocatalyst,wherein the chiral amine solely controls the stereochemistry and offers high levels of stereochemical.A Ni-catalyzed enantioselective,desymmetrizing aza-Heck cyclization of oxime esters has been established with a commercially available chiral pyridinebis(oxazoline)ligand.This reaction is operationally simple,highly reliable and scalable to deliver densely functionalized products,and has been successfully applied to the enantioselective synthesis of 2-substituted-3,7a-dihydro-3aH-indoles.Combined theoretical and experimental studies suggest a triplet state Ni0/Ni? catalytic cycle pathway,including O-N bond cleavage,insertion and ?-H elimination.The ?-H elimination,rather than alkene insertion,was found to be the enantio-determining step.This Ni-catalyzed aza-Heck process provides a sustainable process for the synthesis of chiral nitrogen-containing heterocycles.