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1、ReductionofEnones,a-DiketonesandAcyloinswithNaBH4/Dowex1-x8Bull.KoreanChem.Soc.2003,Vol.24,No.3295MildandEfficientReductionofa,b-UnsaturatedCarbonylCompounds,a-DiketonesandAcyloinswithSodiumBorohydride/Dowex1-x8System*†BehzadZeynizadehandFarhadShiriniChemistryDepa
2、rtment,FacultyofSciences,UrmiaUniversity,Urmia57159-165,Iran†ChemistryDepartment,FacultyofSciences,GuilanUniversity,Rasht41335-1914,IranReceivedAugust12,2002a,b-UnsaturatedaldehydesandketonesareregioselectivelyreducedtothecorrespondingallylicalcoholswithNaBH4/Dowe
3、x1-x8systeminTHFatroomtemperature.Thissystemisalsoefficientfortheconversionofa-diketonesandacyloinstothevicinaldiolsinrefluxingTHF.KeyWords:Sodiumborohydride,Dowex1-x8,a,b-Unsaturatedcarbonyls,a-Diketones,AcyloinsIntroductionNowwewishtoreportanefficientmethodforth
4、eregioselectivereductionofa,b-unsaturatedaldehydesandReductionofa,b-unsaturatedcarbonylcompoundsbyketoneswithNaBH4/Dowex1-x8system.metalhydridescanfollowtwopathways:additiontocarbonylgroup(1,2-reduction)togiveallylicalcoholsoradditiontotheconjugateddoublebond(1,4-
5、addition)togivesaturatedcarbonylcompounds.Duetoimportanceofsyntheticpre-cursorsofallylicalcohols,theregioselectivereductionofResultsandDiscussiona,b-unsaturatedaldehydesandketonesseemstobeaconvenientandeasywaytoobtainthesecompounds.So,thisRegioselective1,2-reducti
6、onofa,b-unsaturatedcarbonyl1compounds.Selective1,2-reductionofa,b-unsaturatedachievementissyntheticallyveryimportant.Inspiteofsubstantialevidence,thereductionpatternofsodiumboro-carbonylcompoundsisusuallyachievedbyusingmodifiedhydrideforconjugatedcarbonylcompounds
7、ishighlytetrahydroborateagents,whichareformed:a)bythesolventdependentandgenerallytheregioselectivityinthesereplacementofhydride(s)withstericallybulkysubstituents2-4reductionsisnotuseful.Theregioselectivereductionoforelectron-withdrawing/releasinggroupsinordertodis
8、cri-thissystemhasstimulatedconsiderableinterest,leadingtominatebetweenthestructuralandelectronicenvironments4,12,22-25thedevelopmentofnewreducingsystems
