columbia大學(xué)有機(jī)化學(xué)課件06_18_19 html

1、6.18Epoxidation of Alkenesare examples of heterocyclic compoundsthree-membered rings that contain oxygenethylene oxidepropylene oxideCHCH3H2CCH2H2COOEpoxidesSubstitutive nomenclature:named as epoxy-substituted alkanes.“epoxy” precedes name of alkane1,2-epoxypropane2-methyl-2,3-epoxybutane1H3C2C34CHC

2、H3H2CCHCH3H3COOEpoxide Nomenclaturecis-2-Methyl-7,8-epoxyoctadecaneHOHProblem 6.17Give the IUPAC name, including stereochemistry, for disparlure.O+CRCOOHperoxy acidCO+RCOHCCOEpoxidation of AlkenesO+ CH3COOHO+ CH3COHO(52%)ExampleO+CRCOOHCsyn additionO+RCOHCCOStereochemistry of EpoxidationHOHProblem 6

3、.18Give the structure of the alkene, including stereochemistry, that you would choose as the starting material in a preparation of synthetic disparlure.HHperoxy acidHOHProblem 6.18Give the structure of the alkene, including stereochemistry, that you would choose as the starting material in a prepara

4、tion of synthetic disparlure.ethylene propene2-methylpropene2-methyl-2-buteneH2C=CH2 CH3CH=CH2 (CH3)2C=CH2(CH3)2C=CHCH31224846526More highly substituted double bonds react faster.Alkyl groups on the double bond make it more “electron rich.”Relative Rates of EpoxidationMechanism of Epoxidation6.19Ozo

5、nolysis of AlkenesOzonolysis has both synthetic and analytical applications.synthesis of aldehydes and ketonesidentification of substituents on the double bond of an alkeneFirst step is the reaction of the alkene with ozone. The product is an ozonide.O+O3CCOCCOOzonolysis of AlkenesSecond step is hydrolysis of the ozonide. Two aldehydes, two ketones, or an aldehydeand a ketone are formed.O+O3CCOCCOH2O, Zn+OOCCOzonolysis of AlkenesAs an alternative to hydrolysis, the ozonide canbe treated with dimethyl sulfide.O+O3CCOCCO(CH3)2S+OOCC