Efficient green synthesis of biscoumarins catalyzed by disodium tungstate

We describe disodium tungstate as a good catalyst for the synthesis of biscoumarins in the presence of water as a solvent. The proposed method gives expected products from different substituted aromatic aldehydes. This method gives the anticipated products with good yields. This catalyst is also relevant for the gram-scale preparation of the product and short of any supplementary energy (microwave, ultrasonication, ball milling, and thermal heating). All the constructed products were fully characterized by FT-IR, NMR (1H & 13C), and Mass spectra.