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1、Chemoselectivity:selectivereactionsandprotection24ConnectionsBuildingon:Arrivingat:Lookingforwardto:•Carbonyladditionandsubstitution•Regio-,stereo-,andchemoselectivity•Synthesisinactionch25ch6,ch12,&ch14•Reagentsforreductionofalkenesand•Enolatesespeciallyaldolchemistry•Conjugateadditionch10carbonyl
2、compoundsch26–ch29•Mechanismsandcatalysisch13•Removaloffunctionalgroups•Retrosyntheticanalysisch30•Electrophilicadditiontoalkenech20•Reductionofbenzenerings•Cycloadditionsch35•Nucleophilicaromaticsubstitution•Protectionofaldehydes,ketones,•Rearrangementsch37ch23alcohols,andamines•Sulfurchemistrych4
3、6•ReagentsforoxidationofalcoholsSelectivityMostorganicmoleculescontainmorethanonefunctionalgroup,andmostfunctionalgroupscanreactinmorethanoneway,soorganicchemistsoftenhavetopredictwhichfunctionalgroupwillreact,whereitwillreact,andhowitwillreact.Thesequestionsarewhatwecallselectivity.Selectivitycome
4、sinthreesorts:chemoselectivity,regioselectivity,andstereoselectivity.Chemoselectivityiswhichgroupreacts;regioselectivityiswhereitreacts.Stereoselectivityishowthegroupreactswithregardtothestereochemistryoftheproduct.•Therearethreemaintypesofselectivity•Chemoselectivity:whichfunctionalgroupwillreact•
5、Regioselectivity:whereitwillreact•Stereoselectivity:howitwillreact(stereochemistryoftheproducts)Wetalkedalotaboutregioselectivitytwochaptersago,whenyoulearnedhowtopredictandexplainwhichproduct(s)yougetfromelectrophilicaromaticsubstitutionreactions.Thefunctionalgroupisthearomaticring:whereitreactsis
6、thereaction’sregioselectivity.Goingbackfurther,oneofthefirstexamplesofregioselectivityyoucameacrosswasnucleophilicadditiontoanunsaturatedketone.Additioncantakeplaceina1,2-ora1,4-fashion—thequestionofwhichhappens(wheretheunsaturatedketonereacts)isaquestionofregioselectivity,whichwediscussedinChapters
7、10and23.WeshallleavealldiscussionofstereoselectivityuntilChapters31–34.OregioselectivebrominationOregioselectiveofaromaticamideconjugateadditionNuHNMeHNMe?NuO?Br2/AcOHroomtemperatureOaromaticringreactsregio
