氯苄羟基保护

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1、OrganicSyntheses,Coll.Vol.7,p.34(1990);Vol.63,p.214(1985).INDOLESFROM2-METHYLNITROBENZENESBYCONDENSATIONWITHFORMAMIDEACETALSFOLLOWEDBYREDUCTION:4-BENZYLOXYINDOLE[1H-Indole,4-(phenylmethoxy)-]SubmittedbyAndrewD.Batcho1andWillyLeimgruber2.CheckedbyDavidJ.Wustrowan

2、dAndrewS.Kende.1.ProcedureA.6-Benzyloxy-2-nitrotoluene.Astirredmixtureof124.7g(0.81mol)of2-methyl-3-nitrophenol(Note1),113.2g(0.90mol)ofbenzylchloride,112.2g(0.81mol)ofanhydrouspotassiumcarbonate,and800mLofdimethylformamide(DMF)isheatedat90°Cfor3hr.MostoftheDMFi

3、sremovedonarotaryevaporator(20mm)andtheoilyresidueispouredinto400mLof1Nsodiumhydroxideandextractedwithether(3×800mL).Thecombinedextractsaredried(NaSO),filtered,andevaporated24togive203.5gofyellowishsolid.Recrystallizationfrom1Lofmethanolcooledto0°Caffords177.6(9

4、0%)of6-benzyloxy-2-nitrotolueneaspale-yellowcrystals,mp61–63°C3(Note2).B.(E)-6-Benzyloxy-2-nitro-β-pyrrolidinostyrene.Toasolutionof175.4g(0.72mol)of6-benzyloxy-2-nitrotoluenein400mLofDMFareadded102.5g(0.84mol)ofN,N-dimethylformamidedimethylacetal(Note3)and59.8g(

5、0.84mol)ofpyrrolidine.Thesolutionisheatedatreflux(110°C)for3hr(Note4)undernitrogenandallowedtocooltoroomtemperature.Thevolatilecomponentsareremovedonarotaryevaporator,andtheredresidue(Note5)isdissolvedin200mLofmethylenechlorideand1.60Lofmethanol.Thesolutioniscon

6、centratedtoavolumeofabout1.40Lonthesteambathandtheniscooledto5°C.Filtrationandwashingofthefiltercakewith200mLofcoldmethanolaffords209.8gofredcrystals,mp87–89°C(Note6).Themotherliquorsareevaporated,andtheresidueisrecrystallizedfrom50mLofmethanol(5°C)togiveanaddit

7、ional12.30gofredsolid,mp81–83°C(Note7).Thusthetotalyieldis222.1g(95%)ofa15:1mixtureof(E)-6-benzyloxy-2-nitro-β-pyrrolidinostyrene(Note8)and(E)-6-benzyloxy-β-dimethylamino-2-nitrostyrene.C.4-Benzyloxyindole.Toastirredsolutionof162.2g(0.50mol)of(E)-6-benzyloxy-2-n

8、itro-β-pyrrolidinostyrene(Note9)in1LofTHFand1Lofmethanolat30°Cundernitrogenisadded10mLofRaneynickel(Note10)followedby44mL(0.75mol)of85%hydrazinehydrate.Vigorousgasevo