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Unformatted text preview: 583 ESTER ENOLATES Basic ester hydrolysis followed by acidiﬁcation and decarboxylation gives the diketone 3-(2oxopropyl)cycloheptanone as the major product of the reaction sequence.
O O 1. KOH, ethanol–water CHCOCH2CH3 2. H
3. heat CH2CCH3 C
21.14 (b) 3-(2-Oxopropyl)cycloheptanone (52%) CH3 The -carbon atom of the ester bears a phenyl substituent and a methyl group. Only the
methyl group can be attached to the carbon by nucleophilic substitution. Therefore generate
the enolate of methyl phenylacetate with lithium diisopropylamide (LDA) in tetrahydrofuran
(THF) and then alkylate with methyl iodide.
THF C6H5CH2CO2CH3 C6H5CH CH3I C C6H5CHCO2CH3 OCH3
Methyl phenylacetate (c) CH3 Enolate of methyl
2-phenylpropanoate The desired product corresponds to an aldol addition product.
OH O O O CHC6H5 HCC6H5
Therefore convert cyclohexanone to its enolate and then treat with benzaldehyde.
O OH O CHC6H5 1. LDA, THF
3. H3O Cyclohexanone (d ) 1-(2-Oxocyclohexyl)-1phenylmethanol This product corresponds to the addition of the enolate of tert-butyl acetate to cyclohexanone.
CH2COC(CH3)3 O CH2COC(CH3)3
O O Generate the enolate of tert-butyl acetate with lithium diisopropylamide; then add cyclohexanone.
CH3CO2C(CH3)3 1. LDA, THF
3. H3O tert-Butyl acetate Back Forward Main Menu TOC Study Guide TOC OH
(1-hydroxycyclohexyl)acetate Student OLC MHHE Website ...
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