Environmentally green syntheses of Biginelli compounds, some fused and spiro-fused analogues and bis(indolyl)methanes

Department of Chemistry, University of Calcutta, University College of Science and Technology,

92, Acharya Prafulla Chandra Road, Kolkata-700 009, India

E-mail : amarendra.patra@gmail.com Fax : 91-33-23519755

Manuscript received 15 May 2013, accepted 07 January 2014

One-pot synthesis of various known and new 3,4-dihydropyrimidin-2(1H)-ones/thiones, 5-oxooctahydroquinazolin2-ones/thiones and spiro-fused heterocycles are reported using Aliquat^®336 as a phase-transfer catalyst under microwave irradiation in water. This new method provides comparatively better catalyst for both Biginelli and Biginelli-like cyclocondensation, greener and milder reaction conditions, quicker reaction, simpler isolation of products and better yields. Catalysing efficiency of Aliquat®336 in conjunction with (NH₄ )₂ SO₄ was also tested for one pot two-component condensation of aldehydes and indole yielding various bis(indolyl)methanes in excellent yield under conventional heating.