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Synthesis 2011(14): 2261-2267  
DOI: 10.1055/s-0030-1260067
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© Georg Thieme Verlag Stuttgart ˙ New York

Organocatalytic Application of Ionic Liquids: [bmim][MeSO4] as a Recyclable Organocatalyst in the Multicomponent Reaction for the Preparation of Dihydropyrimidinones and -thiones

Sudipta Raha Roy, Pradeep S. Jadhavar, Kapileswar Seth, Kulin K. Sharma, Asit K. Chakraborti*
Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S. A. S. Nagar 160 062, Punjab, India
Fax: +91(172)2214692; e-Mail: akchakraborti@niper.ac.in;
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Publication History

Received 28 April 2011
Publication Date:
10 June 2011 (online)

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Abstract

The organocatalytic potential of 1-butyl-3-methylimidazolium-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 β-keto ester or β-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.

Key words

ionic liquid - organocatalyst - multicomponent reaction - dihydropyrimidinone - dihydropyrimidinethione