Scheme 53.
Addition of a Lewis acid to the reaction mixture helped enhance α selectivity. Reagents and conditions: a) Ph2SO, Tf2O, CH2Cl2, − 72 °C; b) BF3.OEt2 (0.2 eq).
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.