The Biginelli Reaction is a one-pot acid catalysed cyclocondensation of β-keto ester, urea and aromatic aldehyde which leads to the synthesis of functionalised 3,4-dihydro-2(H)-pyrimidinones (DHPMs). This three-component reaction for the synthesis of dihydropyrimidinone and corresponding dihydropyrimidinethiones has now been known for more than a century since first reported in 1893. Owing to the increasing use of Green technology approach, due to its various merits over Classical methodology and as a need for sustainable Chemistry, this reaction has received renewed interest for preparing DHPMs in an environmentally thoughtful manner with improved yields. The classical reaction has been modified in the recent past by using various catalysts and several structural variants in different solvents to synthesize large number of Biginelli type compounds. Also, these DHPMs (synthetic and natural) possess a wide range of pharmacological activities. We hereby wish to compile, in this present review, the literature available methods related to large number of Biginelli type compounds synthesized using eco-friendly technologies. This protocol couples the benefits of Biginelli reaction with that of greener approach for organic transformations, thus facilitating efficient synthesis of bioactive compounds in environmentally benign way.

Background: Microwave irradiation has emerged as a useful synthetic strategy for chemists and drug developers due to enhanced yields, regioselectivity, and faster reaction times. One area of importance in its practice has been the design of spiro compounds, which possess great interest on account of their natural occurrence and medicinal capabilities. The increasingly large number of these scaffolds and unlimited amount of methodologies utilized in their preparation have made them good candidates for the microwave assisted approach. Conclusion: Therefore, this review emphasizes the use of microwave irradiation in the synthesis of spiro heterocyclic compounds.