Synthetic studies toward longeracemine: The intramolecular [4+2] cycloaddition of 3H-pyrroles

Model studies to develop a tetracyclization approach mimicking the proposed biosynthesis of the secodaphnane-type alkaloid longeracemine are described. These studies have culminated in the successful implementation of a 3H-pyrrole [4+2] cycloaddition that delivers a longeracemine-like azabicycle containing three contiguous quaternary stereocenters.