N-protonation vs O-protonation in strained amides: Ab initio study
SCIE
SCOPUS
- Title
- N-protonation vs O-protonation in strained amides: Ab initio study
- Authors
- Cho, SJ; Cui, CZ; Lee, JY; Park, JK; Suh, SB; Park, J; Kim, BH; Kim, KS
- Date Issued
- 1997-06-13
- Publisher
- AMER CHEMICAL SOC
- Abstract
- Protonation plays an important catalytic role in amide bond hydrolysis. Although the protonation site of an amide is Still debatable, O-protonation is generally preferred to N-protonation in ordinary amides. However, N-protonation can be favored in strained molecular systems. To investigate this strain effect systematically, we studied formamide, strained N-formylazetidine, and highly strained N-formylaziridine using ab initio calculations. The electron correlation effect is found to be important in determining the protonation sites of strained amides, since it contributes to stabilize N-protonation somewhat more than O-protonation. Although O-protonation is highly favored in N-formylazetidine as well as in formamide, N-protonation is favored in N-formylaziridine in both aqueous and gas phases. In case of O-protonation, the geometries become planar even for highly strained amides. The presence of polar solvents contributes to stabilize N-protonation more than O-protonation, The planarity found in O-protonated strained amides and the nonplanarity in N-protonated strained amides would have an important bearing in enzymatic reactions as well as in asymmetric syntheses.
- Keywords
- ACYL-TRANSFER-REACTIONS; HYDROLYSIS; WATER; CYCLOADDITIONS; EQUILIBRIA; FORMAMIDE; ENERGIES; ABINITIO; SYSTEMS; SULTAM
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/21293
- DOI
- 10.1021/jo962063z
- ISSN
- 0022-3263
- Article Type
- Article
- Citation
- JOURNAL OF ORGANIC CHEMISTRY, vol. 62, no. 12, page. 4068 - 4071, 1997-06-13
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