An Efficient Synthesis of 3‐(1 H‐ Tetrazol‐5‐yl)coumarins (=3‐(1 H ‐Tetrazol‐5‐yl)‐2 H ‐1‐benzopyran‐2‐ones) via Domino Knoevenagel Condensation, Pinner Reaction, and 1,3‐Dipolar Cycloaddition in Water

A novel straightforward synthesis of 3‐(1 H ‐tetrazol‐5‐yl)coumarins (=3‐(1 H ‐tetrazol‐5‐yl)‐2 H ‐1‐benzopyran‐2‐ones) 6 via domino Knoevenagel condensation, Pinner reaction, and 1,3‐dipolar cycloaddition of substituted salicylaldehydes (=2‐hydroxybenzaldehydes), malononitrile (propanedinitrile), and sodium azide in H 2 O is reported ( Scheme 1 and Table 2 ). This general protocol provides a wide variety of 3‐(1 H ‐tetrazol‐5‐yl)coumarins in good yields under mild reaction conditions.