Comparative Study on the Reactivity of 6-Haloimidazo[1,2-a]pyridine Derivatives towards Negishi- and Stille-Coupling Reactions

✍ Scribed by Maud Hervet; Isabelle Théry; Alain Gueiffier; Cécile Enguehard-Gueiffier

• Book ID: 102256188
• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: German
• Weight: 142 KB
• Volume: 86
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.200390290

✦ Synopsis

Abstract

The scope of the Suzuki‐cross‐coupling reaction of 6‐haloimidazo[1,2‐a]pyridines is dependent on the availability of the (hetero)arylboronic acids. Thus, with the aim to develop expanded applications of (hetero)arylations of imidazo[1,2‐a]pyridines, we investigated the Negishi‐ and Stille‐cross‐coupling reactions at the 6‐position. Remarkably, attempts to apply the Negishi‐cross‐coupling conditions to the organozinc derivative prepared from 6‐haloimidazo[1,2‐a]pyridine via a lithiumzinc exchange led to the 5‐phenyl compound 3 in 54% yield instead of the desired 6‐phenyl isomer (Scheme 1). In contrast, various commercially available halogenated five‐ or six‐membered‐ring heterocycles were efficiently coupled to the 6‐(trialkylstannyl)imidazo[1,2‐a]pyridine under Stille conditions (Table 2).