Consecutive One-Pot Sonogashira–Glaser Coupling Sequence – Direct Preparation of Symmetrical Diynes by Sequential Pd/Cu Catalysis

✍ Scribed by Eugen Merkul; Dominik Urselmann; Thomas J. J. Müller

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 411 KB
• Volume: 2011
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/ejoc.201001472

✦ Synopsis

Abstract

Sonogashira coupling and the catalytic Glaser coupling are both catalyzed by the Pd–Cu complex couple and can be concatenated to a consecutive sequentially Pd/Cu‐catalyzed process in a one‐pot fashion, and air oxygen serves as the only oxidant in the second step. In a pseudo‐four‐component synthesis, a broad variety of symmetrically substituted 1,4‐bis(hetero)aryl‐1,3‐butadiynes are obtained in good to excellent yields. Interestingly, the presence of iodide ions has been found to be advantageous over other halides to trigger the Pd/Cu‐catalyzed Glaser step, and Pd and Cu species, as well as triethylamine as a base, are prerequisite for both couplings, which proceed with higher efficiency if performed in a one‐pot sequence.