Synthesis of 2-amino-3-ethoxycarbonyl-4-aryl-4H,5H-pyrano-[3,2-c]benzopyran-5-one

One Pot Synthesis of Biscoumarins and Pyranocoumarins by Coconut Juice as a Natural Catalyst

Background:

The conception of ‘Green chemistry’ is the much inventive chemistry which is potent and more environmentally benign. It is notable that many organic reactions take place in conventional organic solvents, known as volatile organic compounds. Being concerned about the environmental impact, we report a promoting medium, coconut juice (ACC) for one-pot synthesis of biscoumarins and pyranocoumarins which is safe, harmless, green and environmentally benign.

Methods and Results:

Substituted biscoumarins have been achieved by the reaction of biscoumarin and substituted aromatic aldehydes in presence of ACC which acts as a green catalyst cum solvent. Each reaction showed good to excellent yield in presence of both electron donating as well as electron withdrawing group on aromatic aldehyde without formation of any by-products. Similarly, pyranocoumarins have been achieved by the reaction of biscoumarin, substituted aromatic aldehydes, active methylene nitrile in presence of ACC. All the reactions proceed smoothly and gave higher yields in case of malononitrile in comparison of ethyl-2-cyanoacetate.

Conclusion:

A simple, eco-friendly and novel procedure was demonstrated for the synthesis of biscoumarins and pyranocoumarins using natural feedstock coconut juice. The major importance of using ACC juice is higher yields, no work-up and no column chromatography.

A Green Method for the Synthesis of Novel benzo[b]pyran Derivatives in an Ionic Liquid

A series of novel 2-amino-5,6,7,8-tetrahydro-4,7,7-trimethyl-5-oxo-4-aryl-4 H-benzo[ b]pyran-3-carbonitriles was obtained from the reaction of 2-(1-arylethylidene)malononitrile and 5,5-dimethylcyclohexane-1,3-dione in an ionic liquid at 90°C. This method had the advantages of operational simplicity, mild reaction conditions and an environmentally benign procedure.