Copper-Free Sonogashira Coupling of Acid Chlorides with Terminal Alkynes in the Presence of a Reusable Palladium Catalyst: An Improved Synthesis of 3-Iodochromenones (=3-Iodo-4H-1-benzopyran-4-ones)

✍ Scribed by Pravin R. Likhar; M. S. Subhas; Moumita Roy; Sarabindu Roy; M. Lakshmi Kantam

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: German
• Weight: 157 KB
• Volume: 91
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.200890032

✦ Synopsis

Abstract

Pd/C is used as an efficient catalyst for the copper‐free Sonogashira coupling of acid chlorides and terminal alkynes to afford ynones in high yields (Tables 1 and 3). Cyclization of (2‐methoxyaryl)‐substituted ynones induced by I~2~/ammonium cerium(IV) nitrate (CAN) at room temperature gave 3‐iodochromenones (=3‐iodo‐4__H__‐1‐benzopyran‐4‐ones) in excellent yield (Table 4).