Straightforward Access to 2‑Iodoindolizines via Iodine-Mediated Cyclization of 2‑Pyridylallenes

A metal-free
access to 2-iodo-1,3-disubstituted indolizines has
been developed. The proposed synthesis is relatively simple and efficient
and involves the iodine-triggered 5-endo-trig cyclization of 2-pyridylallene
precursors. While it can be conducted on a gram scale, the preparation
of the precursors is straightforward and does not always require intermediate
purifications. The obtained 2-iodoindolizines can be further functionalized
through cross-coupling reactions.