Electronic structures and reactivities of model β-lactams studied by semiempirical molecular orbital calculations = 반경험적 분자궤도 계산에 의한 모델 베타 락탐의 전자구조와 반응성에 관한 연구

The various properties for 4-membered ring are studied by semiempirical MINDO/3 calculations. Only 1-2 kcal/mol and 5-7 ckal/mol is required to twist the planar model into the conformations of cephalosporins and penicillins. For the leaving group effect, the $\pi$-electron accepting ability is a major effect and the inductive effect is a minor effect in the substituents in our models. Of the various four membered ring substituents, C$_3$-methoxy group and C$_4$-SH group enhance the amide bond breaking of $\beta$-lactam, but C$_4$-OH group does not. We tried to search the simple theoretical parameters that can be correlated with activities for the various active cephalosporins by semiempirical molecular orbital method, and obtained a mixed result. MM calculations are carried out to obtain model cephalosporin structures, and the resulting geometric variables are in reasonable agreement with the experimental values. In NMDO method, enamine resonance and amide resonance could not be expressed accurately. But in the extreme cases, several parameters correlate with the activity.
Advisors
Lee, Yoon-Supresearcher이윤섭researcher
Publisher
한국과학기술원
Issue Date
1989
Identifier
66579/325007 / 000871465
Language
eng
Description

학위논문(석사) - 한국과학기술원 : 화학과, 1989.2, [ vi, 57 p. ]

URI
http://hdl.handle.net/10203/32551
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=66579&flag=t
Appears in Collection
CH-Theses_Master(석사논문)
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