Abstract
7-Oxanorbornadienes are valuable synthetic intermediates as they can serve as general templates to create highly substituted ring systems. However, to date, only very few C1-substituted 7-oxanorbornadienes have been synthesized and can be found in the literature. In this article, synthesis of some C1-substituted 7-oxanorbornadienes was achieved by the Diels–Alder reaction between 2-substituted furans and dimethylacetylene dicarboxylate. Moderate to good yields (13–85%) of the Diels–Alder reactions were observed. These C1-substituted 7-oxanorbornadienes will find applications as valuable synthetic intermediates and are useful in the studies of transition-metal-catalyzed reactions.
GRAPHICAL ABSTRACT
ACKNOWLEDGMENTS
This work was supported by Merck Frosst Centre for Therapeutic Research, Natural Sciences and Engineering Research Council of Canada (NSERC), and Boehringer Ingelheim (Canada) Ltd.
Notes
a Isolated yield after column chromatography.
b Compound 11k was unstable and was aromatized to form compound 12 in 92% (see Scheme 3).