Synthesis of the First Resorcin[4]arene-Functionalized Triazolium Salts and Their Use in Suzuki–Miyaura Cross-Coupling Reactions

• Main Authors: David Sémeril, Dominique Matt, Rengan Ramesh
• Format: Article
• Language: English
• Published: MDPI AG 2019-04-01
• Series: Catalysts
• Subjects: resorcinarene; triazolium salt; Suzuki–Miyaura cross-coupling
• Online Access: https://www.mdpi.com/2073-4344/9/4/388

Two bulky triazolium salts, namely 1-{4(24),6(10),12(16),18(22)-tetramethylenedioxy- 2,8,14,20-tetrapentylresorcin[4]arene-5-yl}-4-phenyl-3-methyl-1<i>H</i>-1,2,3-triazolium tetrafluoro borate (<b>1</b>) and 1,4-bis{4(24),6(10),12(16),18(22)-tetramethylenedioxy-2,8,14,20-tetrapentyl resorcin[4]arene-5-yl}-3-methyl-1<i>H</i>-1,2,3-triazolium iodide (<b>2</b>), have been synthesized and assessed in the palladium-catalyzed Suzuki&#8722;Miyaura cross-coupling of aryl chlorides, with aryl boronic acids. As a general trend, the reaction rates obtained with <b>1</b> were significantly higher (up to 5 times) than those observed for <b>2</b>, this mainly reflected a sterically more accessible metal center in the catalytic intermediates formed with <b>1</b>. The presence of flexible pentyl chains in these intermediates, which might sterically interact with the metal center, when the latter adopts an exo-orientation with respect to the cavity, were likely responsible for the observed good performance.