Diels–Alder Reaction of Cyclopentadiene and Alkyl Acrylates in the Presence of Pyrrolidinium Ionic Liquids with Various Anions

Abstract

The conversion and stereoselectivity of transformation to endo and exo norbornene derivatives was determined in the Diels–Alder reaction of cyclopentadiene with alkyl acrylates. The reactions were carried out in the pyrrolidinium ionic liquids in the presence of metal chlorides and trifluoromethanesulfonates as the catalysts. Shorter reaction times and higher conversions of dienophile were observed in a comparison with analogous cycloadditions carried out in the presence of conventional organic solvents. A higher stereoselectivity to the endo isomer was found in the majority of cases. The ionic liquids composed of 1-butyl-1-methylpyrrolidinium cation (Pyrr1.4) and various anions were used. The influence of ionic liquid anion and several metal chlorides and metal triflates used as the catalysts on the conversion was determined. The conversion and stereoselectivity of transformation to endo and exo norbornene derivatives was determined in the Diels–Alder reaction of cyclopentadiene with alkyl acrylates. The reactions were carried out in the pyrrolidinium ionic liquids in the presence of metal chlorides and trifluoromethanesulfonates as the catalysts. Shorter reaction times and higher conversions of dienophile were observed in a comparison with analogous cycloadditions carried out in the presence of conventional organic solvents. A higher stereoselectivity to the endo isomer was found in the majority of cases. The ionic liquids composed of 1-butyl-1-methylpyrrolidinium cation (Pyrr1.4) and various anions were used. The influence of ionic liquid anion and several metal chlorides and metal triflates used as the catalysts on the conversion was determined.