《糖生物学》课程教学课件（讲稿）09 glycosylation

9.1 Chemical disaccharideformation -2

9.1$Chemical$disaccharide$ forma2on$42$

3.5TrichloroacetimidatesRCROCl3CN1RONHCl3CSimilaritybetweenanomerictrichloroacetimidateformation and the acetylation rxns, either the α- or βanomeric acetates could be formed preferentially underdifferentrxnconditions

3.5$Trichloroace.midates Similarity$between$anomeric trichloroace2midate forma2on$and$the$acetyla2on$rxns,$either$the$α4$or$β4 anomeric$acetates$could$be$formed$preferen2ally$under$ different$rxn$condi2ons$

OBnOBnBnOCBnO-OHBnOBnOCl3CCNOBnOBnNHKinetic controlbaseOBnOBnCCNaHBnOBnOBnOBnOOBhCl,CCNOBnOH0CCl3NHThermodynamic control

Kine2c$control Thermodynamic$control

OBnOBnCOOMeHOBnOBnOBF3Et20N3BnOBnON3N3OCCl3OCCl3NHNF3B+HNon-neighbouringgroupparticipationSn2 type rxnOBnInversion of configurationOMeBnOBnON3N3Neighbouringgroupparticipation SN1 rxn

Non4neighbouring$group$ par2cipa2on$ SN2$type$rxn$$ Inversion$of$configura2on$ Neighbouring$group$ par2cipa2on$SN1$rxn$$

(a)hydrazineacetate,DMF,2h,rtAcoOAC(b)Cs2CO3,trichloroacetonitrileCH2Cl2, 2h, rt64%CCl3OAcNH

3.6GlycalsOBnROHOBnBnOZnCl2BnOORBnOBnOOOHOBnBnONISBnOOBnOBnorIDCP.0BnOBnOBnOBnOORROHOBnBusSnHBnOBnOorH2/PdOR

3.6$Glycals

3.7miscellaneousonesOFCNHPh(OP)n(OP)nNPhBaseOCF3(OP)nPTFAIDonor0HORNPhORLewis acidCICF3(OP)HORR1OR(OP)n(OP)nRAuB.Yu,Acc.Chem.Res.2012doi10.1021/ar200296m

B.$Yu,$Acc.$Chem.$Res.$2012$doi$10.1021/ar200296m$ 3.7$miscellaneous ones

4Controlofstereochemistry4.1Neighbouringgroupparticipation4.2SolventOBn?BnOHOHNOBnOBnOBnCCl3OOMeCBnOBnOTMSOTfBnOBnOMeCNBnOOBn1ICOBnOBnMeCBnOOBnOSn2-BnOOBnOBnOMeα:β= 24:1

4$Control$of$stereochemistry$ 4.1$Neighbouring$group$par.cipa.on$ 4.2$Solvent$

4.3Moleculartethering----intramolecular aglycondelivery (IAD)BnOBnORBnOBnOBnOBnOBnOOHBnORBnO

4.3$Molecular$tethering$EEEE$intramolecular aglycon$$ delivery$(IAD)$

BnOOH.0BnOexcessMe2SiCl2BnOBnOCBnOBnOSEtSEtOHOBnOBnOOBnOMeBnoOHBnONISBnOBnoBnOBnOBnOBnoBnOBnOOBnBnOMeSEtβ onlyOMe