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1、ReviewsK.MaruokaandT.OoiDOI:10.1002/anie.200601737AsymmetricSynthesisRecentAdvancesinAsymmetricPhase-TransferCatalysisTakashiOoiandKeijiMaruoka*Keywords:asymmetricsynthesis·chiraloniumsalts·crowncompounds·enantioselectivity·phase-transfercatalysisAngewandteChemie4222www.an
2、gewandte.org2007Wiley-VCHVerlagGmbH&Co.KGaA,WeinheimAngew.Chem.Int.Ed.2007,46,4222–4266AngewandtePhase-TransferCatalysisChemieTheuseofchiralnonracemiconiumsaltsandcrownethersasFromtheContentseffectivephase-transfercatalystshavebeenstudiedintensively1.Introduction4223prima
3、rilyforenantioselectivecarbon–carbonorcarbon–heteroatombond-formingreactionsundermildbiphasic2.GeneralMechanismofAsymmetricconditions.AnessentialissueforoptimalasymmetriccatalysisPhase-TransferCatalysis4224istherationaldesignofcatalystsfortargetedreaction,whichallowsgenera
4、tionofawell-definedchiralionpairthatreacts3.Alkylation4225withelectrophilesinahighlyefficientandstereoselective4.MichaelAddition4251manner.Thisconcept,togetherwiththesyntheticversatilityofphase-transfercatalysis,providesareliableandgeneralstrategy5.AldolandRelatedReactions
5、4257forthepracticalasymmetricsynthesisofhighlyvaluableorganiccompounds.6.DarzensReaction42577.NeberRearrangement42588.Horner–Wadsworth–EmmonsReaction42591.Introduction9.Cyclopropanation4259In1971,Starksintroducedtheterm“phase-transfercatalysis”toexplainthecriticalroleoftet
6、raalkylammonium10.Epoxidation4259+orphosphoniumsalts(QX)inthereactionsbetweentwo[1]substanceslocatedindifferentimmisciblephases.For11.Aziridination4261example,thedisplacementreactionof1-chlorooctanewithaqueoussodiumcyanideisacceleratedmanythousandfoldby12.Oxidation4262the
7、additionofhexadecyltributylphosphoniumbromide(1)asaphase-transfercatalyst(Scheme1).Keytothistremendous13.Reduction4262enhancementinreactivityisthegenerationofaquaternaryphosphoniumcyanide,whichmakesthecyanideanionsoluble14.Fluorination4263inorganicsolventsandsufficientlynu
8、cleophilic.Thehighrateofdisplacementismainlyduetotwoofthethreecharacter-15.Sulfenylation4
