In search of inexpensive and environmentally benign catalysts, tetraalkylammonium salts were tested alternatively as catalysts for Biginelli reaction in water, which was easily available, harmless and environmentally benign solvent [31-35]. In this paper, we have reported the synthesis of dihydropyrimidinones by Biginelli reaction in aqueous sodium hydroxide under phase transfer catalysis using tetrabutylammonium bromide (TBAB) or chloride (TBAC) or methyltrioctylammonium chloride (Aliquat-336) as phase transfer agent.
We have presented the synthesis of some 3,4-dihydropyrimidinones using quaternary ammonium salts in aqueous sodium hydroxide. The yield of Biginelli product increased according to the size of the cation of the quaternary ammonium salt. The use of quaternary ammonium salt leads to an exaltation of the basicity of hydroxide anion, which is transferred to organic phase
Organic Synthesis Collective Volume 3: E
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