Synthesis of Quinolines from N-Tosyl-1-azadienes

Abstract

A route to aryl-substituted quinolines from N-tosyl 1-azadienes is described. The key steps are a [4 + 2] cycloaddition with benzyne followed by base treatment of the 1,4-dihydroquinoline product. The N-tosyl 1-azadienes were prepared from readily accessible cinnamaldehyde and chalcone substrates by condensation with p-TsNH₂.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.

GRAPHICAL ABSTRACT

Keywords:

• 1-Azadienes
• benzyne
• [4 + 2] cycloaddition
• quinoline synthesis

ACKNOWLEDGMENTS

We thank the National Institutes of Health through Grant No. 1 R15 GM088780-01 for financial support of this research. The NMR data were made possible through NSF CRIF Award 0840220, which supported the acquisition of a 600-MHz NMR. We also thank Jonathan R. Frisch and the X-ray Crystallographic Laboratory at Mississippi State University for the structure of azadiene 6b.

Notes

^a Isolated yield.

^b previously reported result.^{[ 5 ]}

^c [4 + 2]reaction conditions gave the quinoline product directly.