Establishing the concept of aza-[3 + 3] annulations using enones as a key expansion of this unified strategy in alkaloid synthesis

• Main Authors: Aleksey I. Gerasyuto, Zhi-Xiong Ma, Grant S. Buchanan, Richard P. Hsung
• Format: Article
• Language: English
• Published: Beilstein-Institut 2013-06-01
• Series: Beilstein Journal of Organic Chemistry
• Subjects: alkaloids synthesis; catalysis; enones; intramolecular aza-[3 + 3] annulation; N-heterocycles; natural product; vinylogous amides
• Online Access: https://doi.org/10.3762/bjoc.9.131

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.