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Distance-Dependent, Rate-Accelerating and Diastereoselective Directing Effects in Decatungstate-Mediated
Huiming Liang1, Jin Zhu1, Leon Wang1
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Functional groups like amides can accelerate decatungstate (DT) hydrogen atom transfer (HAT) reactions. This proximity-dependent effect enables diastereoselective synthesis of cis-1,2-disubstituted amides via C-H epimerization.
Area of Science:
- Organic Chemistry
- Polyoxometalate Chemistry
- Catalysis
Background:
- Decatungstate (DT) is a key hydrogen atom transfer (HAT) reagent in organic synthesis.
- DT's selectivity is traditionally attributed to steric and electronic factors.
- The rigid structure of DT limits modification for reactivity control.
Purpose of the Study:
- To investigate the influence of innate functional groups on DT-mediated HAT reactions.
- To explore the potential of noncovalent interactions in directing DT reactivity.
- To develop new synthetic strategies for diastereoselective amide synthesis.
Main Methods:
- Utilizing secondary amides as directing groups in DT-mediated HAT.
- Investigating proximity-dependent and diastereoselective effects.
- Employing C-H epimerization of trans-amides to access cis-amides.
Main Results:
- Secondary amides accelerate DT-mediated HAT rates in a proximity-dependent manner.
- The directing effect leads to high diastereoselectivity.
- Successful synthesis of cis-1,2-disubstituted amides from trans-configured starting materials.
Conclusions:
- Noncovalent interactions can effectively guide the reactivity of excited-state DT.
- This discovery challenges existing paradigms for DT selectivity control.
- Opens new avenues for designing tailored DT-mediated HAT strategies.
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