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A regioselective cycloaddition route to isoxazoleboronic esters
M W Davies1, R A Wybrow, C N Johnson
1Department of Chemistry, University of Sheffield, Sheffield, UK S3 7HF.
Chemical Communications (Cambridge, England)
|September 21, 2002
Summary
Alkynylboronates react with nitrile oxides in 1,3-dipolar cycloadditions to form isoxazoleboronic esters. These intermediates are useful in subsequent Suzuki coupling reactions, demonstrating synthetic versatility.
Area of Science:
- Organic Chemistry
- Synthetic Chemistry
Background:
- Boronate esters are versatile synthetic intermediates.
- 1,3-dipolar cycloaddition reactions are key for heterocycle synthesis.
- Nitrile oxides are reactive 1,3-dipoles.
Purpose of the Study:
- To investigate the reaction of alkynylboronates with nitrile oxides.
- To synthesize novel isoxazoleboronic esters.
- To explore the utility of these esters in cross-coupling reactions.
Main Methods:
- 1,3-dipolar cycloaddition reaction between alkynylboronates and nitrile oxides.
- Purification and characterization of the resulting isoxazoleboronic esters.
- Suzuki coupling reactions utilizing the synthesized isoxazoleboronic esters.
Main Results:
- Alkynylboronates react with nitrile oxides to yield isoxazoleboronic esters with high regioselectivity.
- The synthesized isoxazoleboronic esters are stable and readily purified.
- These intermediates efficiently participate in Suzuki coupling reactions, forming diverse products.
Conclusions:
- The 1,3-dipolar cycloaddition of alkynylboronates with nitrile oxides is an effective method for synthesizing isoxazoleboronic esters.
- Isoxazoleboronic esters are valuable building blocks for further synthetic transformations, particularly in Suzuki couplings.