Scheme 3. Heterocycle Formation via Annulation Reactions.
π-Conjugation is implicit in shaded rings. Numbers correspond to representative schemes and charts.
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.