Scheme 2.
Synthetic route to intermediates 3a-9c. Reagents and conditions: (i). Cl2SO, reflux, 2 h; (ii). Et3N, CH3Cl, reflux, <70%; (iii). (AcO)2O, reflux, 30 min.
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.