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Background: Lemon peel powder was used as a natural catalyst for the synthesis of biscoumarins and 3,4-dihydropyrano[c]chromene derivatives. The catalyst is natural, biodegradable, environmentally benign and thus contributes a valuable addition to the existing sustainable methods for the synthesis of coumarin derivatives. Objective: Development of Green synthesis and use of Natural catalyst. Methods: Lemon peel powder was used as a natural, biodegradable, environmentally benign heterogenous catalyst for the synthesis of coumarin derivatives. Results: Natural lemon peel powder was successfully used as a heterogeneous catalyst for the synthesis of coumarin based heterocyclic compounds. Conclusion: In conclusion, an environmentally benign, green and one-pot multicomponent protocol has been developed for the synthesis of biscoumarins and 3,4-dihydropyrano[c]chromene derivatives using lemon peel powder as a natural and biodegradable catalyst. Lemon peel being natural, the present approach is sustainable and will highlight the emerging applications of natural resources for synthetic organic transformations. This protocol offers several advantages such as high yields, clean reaction conditions, and no pollution threat to the environment making it a useful and attractive process for the synthesis of coumarin derivatives.

: Synthesis of isoxazole structural heterocyclic compounds is important due to their wide range of biological activities. In the present article, we report a convenient and easy method for the synthesis of 4-arylmethylidene-3-substituted-isoxazol-5(4H)-ones by the one-pot three-component reaction of aldehydes, β-keto ester, and hydroxylamine hydrochloride cat-alyzed by sulfated tin oxide as a heterogeneous catalyst.