title: Establishing the concept of aza-[3 + 3] annulations using enones as a key expansion of this unified strategy in alkaloid synthesis.
abstract: 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.
authors.affiliation: Division of Pharmaceutical Sciences, School of Pharmacy, and Department of Chemistry, University of Wisconsin, Madison, WI 53705, USA.
authors.forename: Aleksey I
authors.initials: AI
authors.lastname: Gerasyuto
authors.forename: Zhi-Xiong
authors.initials: ZX
authors.lastname: Ma
authors.forename: Grant S
authors.initials: GS
authors.lastname: Buchanan
authors.forename: Richard P
authors.initials: RP
authors.lastname: Hsung
keywords: N-heterocycles; alkaloids synthesis; catalysis; enones; intramolecular aza-[3 + 3] annulation; natural product; vinylogous amides