Calix[n]arene-Catalyzed Three-Component Povarov Reaction: Microwave-Assisted Synthesis of Julolidines and Mechanistic Insights

J Org Chem. 2018 Feb 16;83(4):1761-1771. doi: 10.1021/acs.joc.7b02532. Epub 2018 Feb 2.

Abstract

A new one-pot cascade reaction-based application of Povarov reactions with a p-sulfonic acid calix[4]arene catalyst for the synthesis of a series of 34 julolidine derivatives with substituents at C8 or C9 in good to excellent yields is reported. These microwave-assisted reactions proceeded efficiently, had short reaction times, were metal-free, were low cost, and used an inexpensive, easily available and nontoxic catalyst. These advantages, along with a simple workup procedure, make this protocol a very efficient and green alternative to the traditional methods for constructing these types of N-heterocyclic skeletons. In addition, this protocol allows the formation of julolidine structures, which requires the construction of four new C-C bonds and two C-N bonds. A mechanism for the Povarov reaction involving a stepwise sequence via ionic intermediates was proposed and validated.

Publication types

  • Research Support, Non-U.S. Gov't