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Solid-phase Synthesis of [4.4] Spirocyclic Oximes
Published on: February 6, 2019
Modulations in restricted amide rotation by steric induced conformational trapping
V V Krishnan1, William B Thompson, Kalyani Maitra
1Department of Chemistry, California State University, Fresno CA 93740.
Chemical Physics Letters
|February 11, 2012
Summary
A modification to N,N-diethyl-o-toluamide (o-DEET) changes amide bond rotation dynamics. Steric interactions create a three-site exchange, unlike the classic two-site exchange seen in N,N-diethyl-m-toluamide (m-DEET).
Area of Science:
- Organic Chemistry
- Physical Chemistry
- Chemical Dynamics
Background:
- Restricted rotation around amide bonds is crucial in molecular dynamics.
- N,N-diethyl-m-toluamide (m-DEET) serves as a model for studying chemical exchange phenomena.
- Understanding conformational dynamics is key to predicting molecular behavior.
Purpose of the Study:
- To investigate the impact of steric hindrance on amide bond rotation.
- To explore the conformational dynamics of N,N-diethyl-o-toluamide (o-DEET).
- To characterize the transition from two-site to three-site chemical exchange.
Main Methods:
- Variable-temperature Nuclear Magnetic Resonance (NMR) spectroscopy.
- Two-dimensional exchange spectroscopy (2D-EXSY).
- Computational molecular modeling studies.
Main Results:
- Steric interactions in o-DEET introduce a third, higher-energy conformation.
- The restricted rotation around the amide bond shifts from a two-site to a three-site exchange.
- NMR and modeling data confirm the altered dynamic landscape of o-DEET.
Conclusions:
- Steric effects from ortho-substituents significantly influence amide bond rotational dynamics.
- o-DEET exhibits a more complex conformational exchange than previously understood.
- This study highlights the importance of subtle structural modifications in altering chemical dynamics.
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