Sequential One-Pot Vilsmeier–Haack and Organocatalyzed Mannich Cyclizations to Functionalized Benzoindolizidines and Benzoquinolizidines

The development of
new one-pot sequential
cyclizations involving a Vilsmeier–Haack reaction followed
by an organocatalyzed Mannich reaction is reported. This synthetic
strategy gives access to functionalized indolizidines and quinolizidines
in one operation from readily synthesized precursors. Yields and diastereoselectivities
are good to excellent when formamides are used to trigger the key
step, bearing either an electron-rich aryl or a pyrrole as the nucleophilic
partner in the first cyclization.