醚氨基及氨基酸的各种保护基及去保护方法大全.docx
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醚氨基及氨基酸的各种保护基及去保护方法大全.docx
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醚氨基及氨基酸的各种保护基及去保护方法大全
醚、氨基及氨基酸的各种保护基及去保护方法大全
(整理有详细操作)
[Acetate][Benzoatel][Pivaloate][Levulinate][BacktoCarb.Synthesis]
Ac-(acetate)ester
StandardProtectionProcedure
Toasolutionoftheglycosideindrypyridine(25eq)underaninertatmosphereatroomtemperature,aceticanhydride(10eq)isaddedandstirreduntilcompletebyTLC(usually16h). Thereactionmixtureisthenpouredintoice/waterandextractedthreetimeswithchloroform. Thecombinedorganiclayersareextractedwith3%HCl,saturatedaqueoussodiumbicarbonate,andwater. Theorganiclayeristhendriedandconcentratedinvacuo. Theresultingresidueispurifiedbyflashchromatography(SiO2)ifnecessary.
Removal
Theglycosideisdissolvedinmethanolandasolutionofsodiummethoxideinmethanol(0.1eqper-OAc)isaddeddropwiseat0°. ThesolutioniswarmedtoroomtemperatureandstirredunderaninertatmosphereuntilcompletebyTLC(usuallywithinafewhours). AmberlitecationicexchangeresinisthenaddedwithvigorousstirringuntilthepHofthemixtureisneutral. Themixtureisthenfilteredandconcentrated. Theresultingresidueispurifiedbyflashchromatography(SiO2)ifnecessary.
OR
TheGlycosideisdissolvedinmethanolandhydrazinehydrate(15eqper-OAc)isaddedintwoportionsover1.5hours. ThesolutionisstirredatroomtemperatureunderaninertatmosphereuntilcompletebyTLC(usually6hours). Thesolutionisthenneutralizedwithglacialaceticacid. Themixtureisfilteredthroughceliteandconcentrated. Theresultingresidueispurifiedbyflashchromatography(SiO2)ifnecessary.
References
J.Org.Chem.,1996,61,6442-6445.
"SyntheticMethodsforCarbohydrates"Lemieux,Ch6,pg.90-115.
J.Chem.Soc.,PerkinTrans.1,1996,985-993.
Bz-(benzoate)ester
StandardProtectionProcedure
Toasolutionoftheglycosidedissolvedindrypyridine(0.3M),benzoylchloride(4eqper-OH)isaddedatroomtemperatureunderaninertatmosphereandstirreduntilcompletebyTLC(usually16h). Methanolisaddedandthesolutionwasconcentratedinvacuo. TheresiduewasdissolvedinDCMandwashedwithwater,saturatedcoppersulfate,andbrine. Theorganiclayerisdriedandconcentratedinvacuo. Theresultingresidueispurifiedbyflashchromatography(SiO2)ifnecessary.
Removal
TheglycosideisdissolvedinMeOHandasolutionofNaOH(2.5eqper-OH)inMeOHisaddedslowly. ThemixtureisstirredatroomtemperatureunderaninertatmospheretillcompletebyTLC(usually1h)andthenconcentratedinvacuo. Theresidueisdissolvedinethylacetateandtheorganicsolutioniswashedtwicewithwater,dried(sodiumsulfate),andconcentratedinvacuo. Theresultingresidueispurifiedbyflashchromatography(SiO2)ifnecessary.
References
Tetrahedron,1970,26,803-812.
Carb.Res.,1993,244,237-246.
Piv-(pivaloate)ester
StandardProcedure
Theglycosideisdissolvedinpyridine:
DCM2:
1andcooledto-20°. PivCl(1.2eqper-OH)isthenaddeddropwiseunderaninertatmosphereandtheresultisstirredat0°untilcompletebyTLC(usually8h). ThemixtureisthendilutedwithDCMandextractedwith5%HCltwiceandoncewithwater. Theorganiclayeristhendried(sodiumsulfate)andconcentratedinvacuo. Theresultingresidueispurifiedbyflashchromatography(SiO2)ifnecessary.
Removal
TheglycosideisdissolvedinMeOH,andasolutionofsodiummethoxideinmethanol(10eqper-OH)isaddeddropwiseatroomtemperatureunderaninertatmosphereandstirreduntilthereactioniscompletebyTLC(usually24h). AqueousHCl(10%)isaddedtothesolutionuntilneutralandtheresultingmixtureisconcentratedinvacuo. Theresidueispurifiedbyflashchromatography(SiO2)ifnecessary.
References
Tet.Asym.2000,295-303.
J.Am.Chem.Soc.1990,112,3693-3695.
Lev-(levulinate)ester
StandardProtectionProcedure
Toasolutionoftheglycosideindrypyridineatroomtemperatureunderaninertatmosphere,levulinicanhydride(2eq)isaddeddropwise. ThereactionwasstirreduntilcompletebyTLC(usually24h)andicewaterisadded. Themixtureisextractedwithchloroformandthentheorganiclayerisbackextractedwithbrine,dried(sodiumsulfate),andconcentratedinvacuo. Theresultingresidueispurifiedbyflashchromatography(SiO2)ifnecessary.
Removal
Theglycosideisdissolvedinpyridineandhydrazinehydrate(1Minpyridine:
aceticacid3:
2)isaddedatroomtemperatureunderaninertatmosphere. AfteradditionofhydrazineissufficienttoconsumestartingmaterialcompletelybyTLC(usuallyafewminutes),pentane-2,4-dioneisaddedwithcoolingtoquenchthereaction. Themixtureisdilutedwithchloroformandextractedoncewithwaterandoncewithbrine. Theorganiclayerisdried(sodiumsulfate)andconcentratedinvacuo. Theresidueispurifiedbyflashchromatography(SiO2)ifnecessary.
References
JACS,1975,97,1614-1615.
Tet.Lett.,1976,52,4875-4878.
[Benzyl][Trityl][PMP][Allyl][pMB][BacktoCarb.Synthesis]
Bn-(benzyl)ether
StandardProtectionProcedure
Toasolutionofsodiumhydride(1.3eqper-OH)inDMF,theglycoside(dissolvedinDMF)isaddeddropwiseat0°underaninertatmosphere. Themixtureisstirredfor30minutesat0°andbenzylbromide(1.3eqper-OH)isaddeddropwise. *Note-acatalyticamountofTBAIorcrownethercanbeadded. ThereactionisstirredatroomtemperatureuntilcompletebyTLC(usually16h)andmethanolisaddedslowlytoquenchthereaction. Thesolutionisthendilutedwithchloroformandwater,extracted3timeswithwaterandoncewithbrine. Theorganiclayerisdried(sodiumsulfate)andconcentratedinvacuo. Theresultingresidueispurifiedbyflashchromatography(SiO2)ifnecessary.
OR
ToasolutionoftheglycosideinDCM,benzyltrichloroacetimidate(2eqper-OH)isaddeddropwise(asasolutionincyclohexane-seethirdreference)withTfOH(catalytic->1mol%). TheresultisstirredatroomtemperatureunderinertatmosphereuntilcompletebyTLC(usuallyovernight). SaturatedaqueoussodiumbicarbonateisaddedandthemixtureisdilutedwithDCM. Theorganiclayerisextractedoncewithwater,oncewithbrine,dried(sodiumsulfate),andconcentratedinvacuo. Theresultingresidueispurifiedbyflashchromatography(SiO2)ifnecessary.
Removal
Theglycosideisdissolvedin1:
1MeOH:
tBuOHandpalladiumhydroxide(0.1eq)isaddedatroomtemperature. Ahydrogenatmosphereisadded(balloonpressure)andthereactionisstirreduntilcompletebyTLC(usually16h). Themixtureisthenfilteredandconcentrated. *Note-catalyticglacialacidicacidmaybeaddedifthereactionisn'tcomplete. Theresultingresidueispurifiedbyflashchromatography(SiO2)ifnecessary.
References
J.Org.Chem.,1979,44,3442.
J.Am.Chem.Soc.,1971,93,1746.
Tr-(triphenylmethyl)ortritylether
StandardProtectionProcedure
Toasolutionoftheglycoside,tritylchloride(1.1eqforprimaryoversecondary,1.5eqforeach-OHotherwise),andtriethylamine(1.5eqforprimaryoversecondary,2eqforeach-OHotherwise)stirringinDMFunderaninertatmosphereatroomtemperature,DMAP(0.05eq)isadded. ThereactionisstirreduntilcompletebyTLC(usuallyovernight)andthenpouredintoice-water. Themixtureisextractedwithchloroformandtheorganiclayeriswashedwithsaturatedaqueousammoniumchlorideandwater,dried(sodiumsulfate),andconcentratedinvacuo. Theresultingresidueispurifiedbyflashchromatography(SiO2)ifnecessary.
Removal
Theglycosideisdissolvedinethanoland5%palladiumoncharcoalisaddedunderahydrogenatmosphere. ThereactionisstirreduntilcompletebyTLC(usuallyovernight)andfiltered. Thesolutionisconcentratedandtheresidueispurifiedbyflashchromatography(SiO2)ifnecessary.
References
Tet.Lett.,1979,2,95-98.
JOC,1978,18,2877-2881.
pMB-(para-methoxybenzyl)ether
StandardProtectionProcedure
Toasolutionofsodiumhydride(1.3eqper-OH)inDMF,theglycoside(dissolvedinDMF)isaddeddropwiseat0°underaninertatmosphere. Themixtureisstirredfor30minutesat0°andpara-methoxybenzylbromide(1.3eqper-OH)isaddeddropwise. *Note-acatalyticamountofTBAIorcrownethercanbeadded. ThereactionisstirredatroomtemperatureuntilcompletebyTLC(usually16h)andmethanolisaddedslowlytoquenchthereaction. Thesolutionisthendilutedwithchloroformandwater,extracted3timeswithwaterandoncewithbrine. Theorganiclayerisdried(sodiumsulfate)andconcentratedinvacuo. Theresultingresidueispurifiedbyflashchromatography(SiO2)ifnecessary.
Removal
TheglycosideisdissolvedinDCM/H2O20:
1andDDQ(upto10eq)isaddedatroomtemperatureunderaninertatmosphere. ThereactionisstirreduntilcompletebyTLC(usually24h,mayrequireheat)anddilutedwithDCM. Thesolutionisextractedwithsaturatedaqueoussodiumbicarbonate,dried(sodiumsulfate),andconcentratedinvacuo. Productcanthenbepurifiedbycolumnchromatographyifnecessary. Theresultingresidueispurifiedbyflashchromatography(SiO2)ifnecessary.
References
JACS,1992,114,2524-2536.
JACS,1996,118,9265-9270.
Allyl-(allyl)ether
StandardProtectionProcedure
Toasolutionofsodiumhydride(1.3eqper-OH)inDMF,theglycoside(dissolvedinDMF)isaddeddropwiseat0°underaninertatmosphere. Themixtureisstirredfor30minutesat0°andallybromide(1.3eqper-OH)isaddeddropwise. *Note-acatalyticamountofTBAIorcrownethercanbeadded. Thereactionisstirredatroomtemperatureuntil
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