Scheme 3.
Synthesis of target compounds 71–74. Reagents and conditions: (a) hydrazine monohydrate, EtOH, reflux, 3 h; (b) CH(OMe)3, PTSA, 85 °C, 2 h or CH3C(OMe)3, HOAc, m-xylene, reflux, 6 h.
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.