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1、TETRAHEDRONLETTERSTetrahedronLetters40(1999)911-914PergamonNewReactivityofMethoxyhydridosilaneintheCatalyticActivationSystem1MakotoHojo,ChikaraMurakami,AtsukoFujii,andAkiraHosomi*DepartmentofChemistryandGraduateSchoolofChemistry,UniversityofTsukuba,Tsukuba,lbaraki305-8
2、571,JapanReceived19October1998;revised12November1998;accepted17November1998AbstractHydroxyestersarereducedbytrimethoxysilaneinthepresenceofacatalyticamountoflithiummethoxidetoyielddiols,whileforsimpleestersthealcoholexchangereactiontakesplacepreferentially.Throughtheex
3、changereaction,lactoneswithoutahydroxygrouparereduced.Tosyliminesarealsoreducedinthesystem.©1999ElsevierScienceLtd.Allfightsreserved.Keywords:Siliconandcompounds;Hypervalentelements;Reduction;CatalysisAmonghighlycoordinatedsiliconspecies,fluorosilicateshavebeenusedfort
4、heselectivetransformationoffunctionalgroupsandthecarbon-carbonbondformationinorganicsynthesis[1,2],whilealkoxy-variantsespeciallyinthecatalyticactivationsystemarenotwellutilized[3-9].Wepreviouslyreportedthestereoselectivereductionofketonesbyalkoxyhydridosilicatesgenera
5、tedfromtrialkoxysilanesandacatalyticamountofalkoxides[10,11].Wedescribehereaninterestingfeatureinthereactivityofalkoxyhydridosilicatesgeneratedinthecatalyticactivationsystem,theselectivereductionofhydroxyesters,lactonesandimines.Wefoundthatmethylmandelate(la)wasconvert
6、edtophenylethane-l,2-diol(2a)bytrimethoxysilaneinthepresenceof6mol%oflithiummethoxide(eq1,R=Ph,m=0).Otherhydroxyesters1werealsoreducedtothecorrespondingdiols2.2TheseresultsaresummarizedinTable1."~mcat.LiOMe"~mR02Et+(MeO)3Si-H,-(I)THFROH12Studiesonorganosiliconchemistry
7、.No.146.ForNo.145,see,ItoH,IshizukaT,TateiwaJ,SonodaM,HosomiA.J,Am.Chem.Soc.inpress.Atypicalprocedureisasfollows.ToasolutionoflithiummethoxideinTHFpreparedat0°Cfor30minfrommethanol(0.06mmol,2.43I.tL)indryTHF(1.2mL)andbutyllithium(1.64Mhexanesolution,0.06mmol,37p.L),tri
8、methoxysilane(3.5mmol,428nag,446lxL)andla(1retool)wereadded,andthemixturewasrefluxedfor9.5hundernitrogen.Aftercooling
