手性化合物結(jié)構(gòu)鑒定

Chirality

DirectchiraldiscriminationinNMR

Thecalculatedisotropiccomponentoftheprotonmagneticshieldingpolarizabilityforhydrogenperoxide(H2O2)isshownasafunctionofdihedralangle(_,asdefinedintheinset).ThetwoenantiomersareR-HOOHfordihedralangles<180°andS-HOOHfordihedralangles>180°.o(l)(N)isobtainedfromfinitefieldcalculationsattheSCFlevel.Thesolidlineistoguidetheeye,and1ppma.u.=1.9446_10-18m/V.

Nuclearmagneticresonance(NMR)spectroscopyisanimportanttechniquefordeterminingthestructureofmoleculesinsolution.NMRcan,however,notyetbeusedtodeterminetheabsoluteconfigurationofchiralmoleculesinapureliquid,asthechemicalshiftsandspin-spincouplingconstantsareidenticalforthetwoenantiomersofachiralmolecule.AllNMR-basedmethodsforchiraldiscriminationhavethereforerequiredthatthechiralsolutebeinthepresenceofachiralreagentorsolvent.

However,theelectric-fieldperturbedchemicalshifttensor,thenuclearmagneticshieldingpolarizabilityo(1)(N),givesrisetothreechiralNMReffectsinaliquidthatcouldmakeitpossibletodiscriminatedirectlybetweentheenantiomersofachiralmolecule:Thecoherentprecessionofnuclearspinsfollowingapplicationofan/2pulsetoanopticallyactiveliquidwillleadtoarotatingmacroscopicelectricpolarization[1];alaserpolarizedintheplaneperpendiculartothefieldofthemagnetmayinprinciplegiverisetochiralchemicalshifts;andtheapplicationofan(oscillating)electricfieldatrightanglestothemagneticfieldofthespectrometermaygiverisetoamagnetizationoscillating(atauniquefrequency)inthedirectionofthepermanentmagneticfield[2].Usingfinitefieldcalculationsonsmallchiralmoleculesweestimatethemagnitudeofb(l)(N)[2].

ThisworkisincollaborationwithProf.A.D.BuckinghamintheDepartmentofChemistryattheUniversityofCambridge.Furtherdetailscanbefoundin:

[1]A.D.Buckingham,Chem.Phys.Lett.,398(2004)1.

[2]A.D.BuckinghamandP.Fischer,Chem.Phys.,324(2006)111-116.DiscriminationofChiralCompoundsUsingNMRSpectroscopy

DiscriminationofChiralCompoundsUsingNMRSpectroscopy

T.J.Wenzel

ISBN:978-0-471-76352-9

Hardcover

576pages

April2007

/WileyCDA/Wi

...tCd-0471763527.htmlAcomprehensiveoverviewoftheuseofNMRspectroscopyforchiraldiscriminationDiscriminationofChiralCompoundsUsingNMRSpectroscopyconciselycoversthebroadarrayofreagentsthatmakeitpossibletodeterminetheopticalpurityandassigntheabsoluteconfigurationofmanyclassesofcompounds.ItdescribeschiralNMRderivatizingagents,solvatingagents,metal-basedreagents,andliquidcrystalsanddiscussestherangeandtypesofcompoundsforwhichtheycanbeusedforanalysis.Afteranoverviewofchiralreagentsandmethodologies,thisreference:IncludescomprehensivecoverageofthechiralreagentsthathavebeenreportedCatalogstherangeofcompoundsforwhichdifferentreagentshavebeenshowntobeeffective

Includesspecialtycategoriessuchasliquidcrystals,ionicliquids,andtheformationofchiralaggregatesfromachiralbuildingblocksthatdonotfitintothebroadercategories

Offersexperimentalstrategiesforusingthereagentsthatarelikelytoimprovethequalityoftheresults

Thisguidedescribesthevarioussystemsandtheiroverallutility,butgoesfurthertoshowthefullscopeofthefieldasawayofguidinginvestigationsintotheoptimalchiralreagentsforuseinNMRspectroscopy.It'sapracticalreferencefororganicchemistsinthepharmaceuticalindustry,academia,andotherareas,NMRspectroscopists,andresearchersinvolvedintheisolationandstructuredeterminationofnaturalproducts.

Chapter1.Introduction.

Chapter2.Aryl-containingCarboxylicAcids.

Chapter3.OtherCarboxylicAcid-BasedReagents.

Chapter4.Hydroxyl-andThiol-ContainingReagents.

Chapter5.Amine-basedReagents.

Chapter6.MiscellaneousOrganic-BasedChiralDerivatizingandSolvatingAgents.Chapter7.ReagentsIncorporatingPhosphorus,Selenium,Boron,andSiliconAtoms.Chapter8.HostCompoundsasChiralNMRDiscriminatingAgents.

Chapter9.ChiralDiscriminationwithMetal-BasedReagents.

Chapter10.ChiralNMRDiscriminationwithHighlyOrderedSystems.

ThomasJ.Wenzel,PHD,istheCharlesA.DanaProfessorofChemistryatBatesCollegeinLewiston,Maine.HehasreceivedresearchandeducationalgrantsfromtheNational