Elsevier

Tetrahedron Letters

Volume 57, Issue 18, 4 May 2016, Pages 1994-1996
Tetrahedron Letters

Synthesis of fused azacycle via Overman rearrangement and ring-rearrangement metathesis as key steps

https://doi.org/10.1016/j.tetlet.2016.03.087Get rights and content

Highlights

  • Highly atom economic reactions are used to generate azacycle.

  • Overman rearrangement in combination with metathesis strategy is demonstrated.

  • Fused azacycle is synthesized by ring-rearrangement metathesis.

  • Amino norbornene derivatives prepared by Overman rearrangement.

Abstract

A simple and concise approach to fused tricyclic compound containing five stereogenic centers and one nitrogen atom is described starting with a readily available building block dicyclopentadiene. This route involves the Overman rearrangement and ruthenium catalyzed ring-rearrangement metathesis as key steps.

Section snippets

Results and discussion

Our journey toward the synthesis of azacycle 1 begins with the preparation of the key precursor 2 (Fig. 1). In this regard a readily available dicyclopentadiene (5) was oxidized with SeO2 followed by PCC oxidation that delivered the reported tricyclic enone 7.10 Stereo selective 1,2 reduction of enone 7 with DIBAL-H at −78 °C gave the known 1β-dicyclopentadienol (4).11

Next, the 1β-dicyclopentadienol (4) was treated with trichloroacetonitrile in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene

Conclusion

In summary, we have demonstrated the utility of RRM strategy with the norbornene derivative 2 to deliver the tricyclic compound 1 involving a short synthetic sequence. For the first time, we have shown that Overman rearrangement in combination with RRM is a useful strategy to generate azacyclic compound 1. Here, we have used an inexpensive and commercially available starting material such as dicyclopentadiene (5).

Acknowledgements

We thank the Department of Science and Technology (DST), New Delhi for the financial support and the Sophisticated Analytical Instrument Facility (SAIF), IIT-Bombay for recording spectral data. S. K. thanks the Department of Science and Technology for the award of a J. C. Bose fellowship. O. R. thanks the University Grants Commission, New Delhi for the award of a research fellowship.

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