Organocatalytic Application of Ionic Liquids: (bmim) (MeSO_4) as a Recyclable Organocatalyst in the Multicomponent Reaction for the Preparation of Dihydropyrimidinones and -thiones

摘要

The organocatalytic potential of l-butyl-3-methylimida-zolium-based room-temperature ionic liquids has been investigated for the synthesis of dihydropyrimidinones and -thiones by a one-pot multicomponent reaction involving an aldehyde, a beta-keto ester or beta-diketone, and urea or thiourea in excellent yields in short time. Factors that influence the efficiency of the ionic liquid as a catalyst were examined such as the anion and the imidazolium cation, particularly the influence of C2 substitution in the latter. The ionic liquid can be recovered and reused for five consecutive reactions without significant loss of catalytic efficiency. The applicability of the methodology for large-scale reaction highlights its potential for bulk synthesis.