A successful enone version of an intramolecular aza-[3 + 3] annulation reaction is described here. Use of piperidinium trifluoroacetate salt as the catalyst and toluene as the solvent appears to be critical for a successful annulation. We also demonstrated for the first time that microwave irradiation can accelerate aza-[3 + 3] annulation reactions. An attempt to expand the scope of the enone aza-[3 + 3] annulation was made in the form of propyleine synthesis as a proof of concept. While synthesis of the enone annulation precursor was successfully accomplished, the annulation proved to be challenging and was only modestly successful.
Gerasyuto, A. I., Ma, Z. X., Buchanan, G. S., & Hsung, R. P. (2013). Establishing the concept of aza-[3 + 3] annulations using enones as a key expansion of this unified strategy in alkaloid synthesis. Beilstein Journal of Organic Chemistry, 9, 1170–1178. https://doi.org/10.3762/bjoc.9.131