Synthesis of 4,6-diarylpyrimidin-2(1H)-one derivatives from benzyl halides and (1-bromoethyl)benzene under solvent-free conditions

Abstract

A facile synthesis of a series of pyrimidinone derivatives from the reaction of benzyl halides, (1-bromoethyl)benzene and urea in the presence of pyridine N-oxide (PNO) under solvent-free conditions is described. This transformation presumeably occurs via oxidation/cross-aldol condensation/Michael addition/intra molecular cyclization, domino sequence, involving the formation of one C–C bond and two C–N bonds in a single step.

Graphical Abstract

Pyridine N-oxide (PNO) has been demonstrated to be efficient and mild reagent for the one-pot synthesis of 4,6-diarylpyrimidin-2(1H)-ones (DAPMs) from a variety of benzyl halides and (1-bromoethyl)benzene instead of benzaldehydes and acetophenone respectively with short reaction times and excellent yields.

Keywords:

• Biginelli reaction
• multi component reaction
• one-pot synthesis
• pyrimidine
• pyridine
• pyridine N-oxide

Supporting information

¹H NMR spectra for all the compounds and ¹³C NMR spectra for the compounds 4a, 4b, 4f and LC-MS for the compound 4f were reported in the supporting information.

Acknowledgements

We gratefully acknowledge the economic support from the Department of Science and Technology – Science Engineering Research Board (DST-SERB), New Delhi, India (grant no: SB/FT/CS-028/2013 Date: 09.06.2014, 24.09.2015, 12.09.2016).