Dolbier HW Solutions 483 - 2 H 3 C CH 3 CH 2 O Enolate of...

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ESTER ENOLATES 577 ( c ) The two carbons of this diester are not equivalent. Cyclization by attack of the enolate at C-2 gives This -keto ester cannot form a stable enolate by deprotonation. It is present in only small amounts at equilibrium. The major product is formed by way of the other enolate. This -keto ester is converted to a stable enolate on deprotonation, causing the equilibrium to shift in its favor. 21.3 ( b ) Both carbonyl groups of diethyl oxalate are equivalent. The enolate of ethyl phenylacetate attacks one of them. ( c ) The enolate of ethyl phenylacetate attacks the carbonyl group of ethyl formate. 21.4 In order for a five-membered ring to be formed, C-5 must be the carbanionic site that attacks the ester carbonyl.
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Unformatted text preview: 2 H 3 C CH 3 CH 2 O Enolate of ethyl 4-oxohexanoate CH 2 CH 2 C C CH 3 CH 2 O O O 2 CH H 3 C 1 OCH 2 CH 3 HC O C 6 H 5 CHCOCH 2 CH 3 2 O Ethyl 3-oxo-2-phenylpropanoate C 6 H 5 CHCH O COCH 2 CH 3 O C 6 H 5 CHCOCH 2 CH 3 CCOCH 2 CH 3 CH 3 CH 2 O O O O 1 C 6 H 5 CHCCOCH 2 CH 3 COCH 2 CH 3 O O O Diethyl 2-oxo-3-phenylbutanedioate 2 CH 3 CH 2 OCCHCH 2 CH 2 CH 2 COCH 2 CH 3 NaOCH 2 CH 3 O O CH 3 Site of carbanion Enolate attacks this carbon. Ethyl (3-methyl-2-oxocyclopentane)-carboxylate O CH 3 OCH 2 CH 3 O C CH 3 CH 2 OCCHCH 2 CH 2 CH 2 COCH 2 CH 3 NaOCH 2 CH 3 O O CH 3 Site of carbanion Enolate attacks this carbon. Ethyl (1-methyl-2-oxocyclopentane)-carboxylate O O CH 3 CH 2 OC H 3 C...
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