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Multicomponent Condensation Reactions via ortho-Quinone Methides
Emily E Allen1, Calvin Zhu1, James S Panek1
1Department of Chemistry, Center for Molecular Discovery (BU-CMD), Life Science and Engineering Building, Boston University , 24 Cummington Mall, Boston, Massachusetts 02215, United States.
Organic Letters
|March 31, 2017
Summary
Iron(III) salts catalyze efficient synthesis of benzopyrans via ortho-quinone methide intermediates. This method offers a versatile two- and three-component strategy for accessing valuable organic compounds.
Area of Science:
- Organic Chemistry
- Synthetic Methodology
- Catalysis
Background:
- Benzopyrans are important heterocyclic compounds with diverse applications.
- Efficient synthetic routes to substituted benzopyrans are highly sought after in organic synthesis.
- Ortho-quinone methides are reactive intermediates useful in cycloaddition reactions.
Purpose of the Study:
- To develop efficient synthetic strategies for benzopyran synthesis.
- To explore the utility of iron(III) salts as catalysts in organic transformations.
- To investigate the formation and reactivity of ortho-quinone methide intermediates.
Main Methods:
- A three-component reaction involving aldehydes or acetals, electron-rich phenols, and alkenes catalyzed by Iron(III) salts.
- A two-component strategy utilizing 2-(hydroxy(phenyl)methyl)phenols to generate ortho-quinone methides.
- Diels-Alder condensation reactions involving in-situ generated ortho-quinone methides.
Main Results:
- The three-component reaction afforded benzopyrans in up to 95% yield.
- The two-component condensation yielded corresponding benzopyran products in up to 97% yield.
- Both strategies demonstrated efficient access to benzopyrans with good yields and selectivities.
Conclusions:
- Iron(III) catalyzed condensation reactions provide an efficient pathway to ortho-quinone methides.
- The developed two- and three-component strategies offer versatile and high-yielding access to benzopyrans.
- This methodology represents a significant advancement in the synthesis of valuable benzopyran scaffolds.
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