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.
Hydrogen peroxide/dimethyl carbonate: a green system for epoxidation of N-alkylimines and N-sulfonylimines. One-pot synthesis of N-alkyloxaziridines from N-alkylamines and (hetero)aromatic aldehydes