One-Pot Synthesis of Highly Functionalized Pyridines James R. Manning and Huw M. L. Davies
http://pubs.acs.org/doi/abs/10.1021/ja803139k

Scope and Mechanism for Lewis Acid-Catalyzed Cycloadditions
Patrick D. Pohlhaus
http://pubs.acs.org/doi/abs/10.1021/ja8015928