Why is the reaction of ethyl (2-cyanoacetyl)carbamate with ethyl orthoformate highly stereoselective?

Kuang-Sen Sung, Ming Chi Lin, Pin Mei Huang, Bo Ren Zhuang, Robert Sung, Ru Rong Wu

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The reaction of ethyl (2-cyanoacetyl)carbamate (1) with ethyl orthoformate in the presence of acetic anhydride is highly stereoselective and only E-ethyl (2-cyano-3-ethoxyacryloyl)carbamate (E-2) is isolated. The reaction is thermodynamically controlled and the product distribution depends on the relative stability between E-2 and Z-2. Both the resonance stabilization of 1.47 kcal mol-1 and the steric hindrance of 2.28 kcal mol-1 in favour of E-2 contribute to the relative stability (3.75 kcal mol-1) between Z-2 and E-2, which is calculated from four isodesmic reactions, and this is the reason why the reaction of compound 1 with ethyl orthoformate is highly stereoselective. The electron-withdrawing ability of some substituents was evaluated. The sequence of π-accepting ability is C(O)NHC(O)OEt > C(O)NH2 > CN and the sequence of σ-accepting ability is CN > C(O)NHC(O)OEt > C(O)NH2.

Original languageEnglish
Pages (from-to)1183-1189
Number of pages7
JournalJournal of Physical Organic Chemistry
Volume18
Issue number12
DOIs
Publication statusPublished - 2005 Dec 1

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Carbamates
Stabilization
Electrons
anhydrides
stabilization
products
electrons
acetic anhydride

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Organic Chemistry

Cite this

Sung, Kuang-Sen ; Lin, Ming Chi ; Huang, Pin Mei ; Zhuang, Bo Ren ; Sung, Robert ; Wu, Ru Rong. / Why is the reaction of ethyl (2-cyanoacetyl)carbamate with ethyl orthoformate highly stereoselective?. In: Journal of Physical Organic Chemistry. 2005 ; Vol. 18, No. 12. pp. 1183-1189.
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abstract = "The reaction of ethyl (2-cyanoacetyl)carbamate (1) with ethyl orthoformate in the presence of acetic anhydride is highly stereoselective and only E-ethyl (2-cyano-3-ethoxyacryloyl)carbamate (E-2) is isolated. The reaction is thermodynamically controlled and the product distribution depends on the relative stability between E-2 and Z-2. Both the resonance stabilization of 1.47 kcal mol-1 and the steric hindrance of 2.28 kcal mol-1 in favour of E-2 contribute to the relative stability (3.75 kcal mol-1) between Z-2 and E-2, which is calculated from four isodesmic reactions, and this is the reason why the reaction of compound 1 with ethyl orthoformate is highly stereoselective. The electron-withdrawing ability of some substituents was evaluated. The sequence of π-accepting ability is C(O)NHC(O)OEt > C(O)NH2 > CN and the sequence of σ-accepting ability is CN > C(O)NHC(O)OEt > C(O)NH2.",
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Why is the reaction of ethyl (2-cyanoacetyl)carbamate with ethyl orthoformate highly stereoselective? / Sung, Kuang-Sen; Lin, Ming Chi; Huang, Pin Mei; Zhuang, Bo Ren; Sung, Robert; Wu, Ru Rong.

In: Journal of Physical Organic Chemistry, Vol. 18, No. 12, 01.12.2005, p. 1183-1189.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Why is the reaction of ethyl (2-cyanoacetyl)carbamate with ethyl orthoformate highly stereoselective?

AU - Sung, Kuang-Sen

AU - Lin, Ming Chi

AU - Huang, Pin Mei

AU - Zhuang, Bo Ren

AU - Sung, Robert

AU - Wu, Ru Rong

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N2 - The reaction of ethyl (2-cyanoacetyl)carbamate (1) with ethyl orthoformate in the presence of acetic anhydride is highly stereoselective and only E-ethyl (2-cyano-3-ethoxyacryloyl)carbamate (E-2) is isolated. The reaction is thermodynamically controlled and the product distribution depends on the relative stability between E-2 and Z-2. Both the resonance stabilization of 1.47 kcal mol-1 and the steric hindrance of 2.28 kcal mol-1 in favour of E-2 contribute to the relative stability (3.75 kcal mol-1) between Z-2 and E-2, which is calculated from four isodesmic reactions, and this is the reason why the reaction of compound 1 with ethyl orthoformate is highly stereoselective. The electron-withdrawing ability of some substituents was evaluated. The sequence of π-accepting ability is C(O)NHC(O)OEt > C(O)NH2 > CN and the sequence of σ-accepting ability is CN > C(O)NHC(O)OEt > C(O)NH2.

AB - The reaction of ethyl (2-cyanoacetyl)carbamate (1) with ethyl orthoformate in the presence of acetic anhydride is highly stereoselective and only E-ethyl (2-cyano-3-ethoxyacryloyl)carbamate (E-2) is isolated. The reaction is thermodynamically controlled and the product distribution depends on the relative stability between E-2 and Z-2. Both the resonance stabilization of 1.47 kcal mol-1 and the steric hindrance of 2.28 kcal mol-1 in favour of E-2 contribute to the relative stability (3.75 kcal mol-1) between Z-2 and E-2, which is calculated from four isodesmic reactions, and this is the reason why the reaction of compound 1 with ethyl orthoformate is highly stereoselective. The electron-withdrawing ability of some substituents was evaluated. The sequence of π-accepting ability is C(O)NHC(O)OEt > C(O)NH2 > CN and the sequence of σ-accepting ability is CN > C(O)NHC(O)OEt > C(O)NH2.

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