AUTHOR=Maskrey Taber S. , Frischling Madeline C. , Rice Mikhaila L. , Wipf Peter 

TITLE=A Five-Component Biginelli-Diels-Alder Cascade Reaction

JOURNAL=Frontiers in Chemistry

VOLUME=6

YEAR=2018

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2018.00376

DOI=10.3389/fchem.2018.00376

ISSN=2296-2646

ABSTRACT=<p>A new multi-component condensation was discovered during the reaction of a urea, β-keto ester, and formaldehyde. In the presence of catalytic indium bromide, a Biginelli dihydropyrimidinone intermediate was further converted to a five-component condensation product through a formal hetero Diels-Alder reaction. The product structure was confirmed by NMR and NOE analysis, and the proposed stepwise mechanism was supported by the reaction of the Biginelli intermediate with ethyl 2-methylene-3-oxobutanoate.</p>