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β-氨基醇及其衍生物催化的不对称Henry反应和氮杂Henry反应.docx

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β-氨基醇及其衍生物催化的不对称Henry反应和氮杂Henry反应 Introduction Asymmetriccatalysishasbecomeanimportantstrategyinmodernorganicsynthesis,asitallowsthesynthesisofenantiomericallypurecompounds,whichareimportantbuildingblocksforpharmaceuticals,naturalproducts,andmaterials.TheHenryreaction,alsoknownasthenitroaldolreaction,isapowerfulandversatilemethodforthesynthesisofβ-nitroalcohols,whichareusefulintermediatesinmanyorganictransformations.TheasymmetricHenryreaction,whichinvolvestheadditionofanitroalkanetoanaldehydeorketoneinthepresenceofachiralcatalyst,hasbeenextensivelystudiedinrecentyears.Inthisarticle,wewillreviewtherecentadvancesinthedevelopmentofβ-aminoalcoholsandtheirderivativesaschiralcatalystsforasymmetricHenryreactionsandnitrogen-containingHenryreactions. β-AminoalcoholsaschiralcatalystsforasymmetricHenryreactions β-Aminoalcoholsareimportantchiralbuildingblocksforthesynthesisofpharmaceuticalsandnaturalproducts.Inaddition,theyhavebeensuccessfullyusedaschiralauxiliariesandligandsinasymmetriccatalysis.Inrecentyears,β-aminoalcoholshavebeendevelopedaseffectivechiralcatalystsforasymmetricHenryreactions. Thefirstexampleofaβ-aminoalcoholasachiralcatalystforasymmetricHenryreactionswasreportedin2005byKobayashiandco-workers.Theyfoundthat(S)-1-amino-2-indanolcatalyzedtheadditionofnitromethanetovariousaldehydeswithhighenantioselectivity(upto99%ee). Sincethen,varioustypesofβ-aminoalcoholshavebeendevelopedaschiralcatalystsforasymmetricHenryreactions.Theseincludecyclicβ-aminoalcohols,suchas(1S,2R)-1-amino-2-cyclopentanol,(1S,2R)-1-amino-2-cyclohexanol,and(1R,2S,5R)-6,6-dimethylbicyclo[3.1.1]hept-2-en-2-amine,aswellasacyclicβ-aminoalcohols,suchas(R)-phenylglycinoland(R)-2-amino-1-phenylethanol.Thesechiralcatalystshaveshownhighefficiencyandexcellentenantioselectivityinawiderangeofsubstrates. Mechanistically,theasymmetricHenryreactioncatalyzedbyβ-aminoalcoholsfollowsatwo-stepprocess.Inthefirststep,theaminogroupofthecatalystactivatesthealdehydeorketonebyforminganiminiumionintermediate.Inthesecondste