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Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Competition studies in alkyne electrophilic cyclization reactions
Saurabh Mehta1, Jesse P Waldo, Richard C Larock
1Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA.
The Journal of Organic Chemistry
|December 25, 2008
Summary
This study explores functional group reactivity in alkyne electrophilic cyclizations. Key factors influencing reaction outcomes include nucleophilicity, alkyne polarization, and intermediate cation stability.
Area of Science:
- Organic Chemistry
- Synthetic Chemistry
Background:
- Electrophilic cyclization reactions are crucial for synthesizing complex organic molecules.
- Understanding functional group reactivity is essential for controlling reaction pathways and outcomes.
Purpose of the Study:
- To investigate the relative reactivity of different functional groups in electrophilic cyclization of diarylalkynes.
- To identify the key electronic and structural factors governing the regioselectivity of these cyclization reactions.
Main Methods:
- Synthesis of diarylalkynes via sequential Sonogashira coupling reactions.
- Competitive cyclization reactions employing various electrophiles (I2, ICl, NBS, PhSeCl).
- Analysis of reaction products to determine the influence of functional groups on cyclization pathways.
Main Results:
- Demonstrated varying nucleophilicity of functional groups towards electrophilic attack.
- Observed that alkyne triple bond polarization significantly impacts cyclization regioselectivity.
- Correlated the stability of cationic intermediates with the observed reaction outcomes.
Conclusions:
- Functional group nucleophilicity is a primary determinant in alkyne electrophilic cyclizations.
- Alkyne polarization and intermediate cation stability critically influence reaction pathway selection.
- These findings provide valuable insights for designing selective synthetic strategies using electrophilic cyclizations.
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