Synthesis of Chiral Imidazolium Salts from a Carbohydrate and Their Application in Pd-Catalyzed Suzuki–Miyaura Reaction

Abstract

A series of chiral 1-(acetylated glucopyranosyl)-3-substituted-imidazolium salts [3-substitute = n-butyl (1a), 3-bromopropyl (1b), 2-chloromethyl benzyl (1c), and 4-chloromethyl benzyl (1d)] have been synthesized. Preliminary catalytic studies show that these imidazolinium salts are remarkably efficient in Pd-catalyzed Suzuki–Miyaura reaction. Functionalized aryl boronic acids reaction with aryl halides (including aryl iodides, aryl bromides and activated aryl chlorides) using environmentally friendly conditions (ethanol aqueous and ambient). The excellent isolate yields reveal that the bulky carbohydrate unit is promising for the construction of highly active transition-metal catalyst. Four C-1 bonded sugar-containing chiral imidazolium salts 1a–d were synthesized and they all exhibited excellent catalytic activity in Pd-catalyzed Suzuki reactions. Pd/1a is most effective for the coupling of functionalized arylboronic acids with arylhalides including activated arylchlorides in ethanol aqueous under air.