Synthesis of novel benzopyran-connected pyrimidine and pyrazole derivatives via a green method using Cu(ii)-tyrosinase enzyme catalyst as potential larvicidal, antifeedant activities.

A series of benzopyran-connected pyrimidine (1a-g) and benzopyran-connected pyrazole (2a-i) derivatives were synthesized via Biginelli reaction using a green chemistry approach. Cu(ii)-tyrosinase was used as a catalyst in the synthesis of compounds 1a-g and 2a-i via the Biginelli reaction. The as-synthesized compounds were characterized by IR, 1 H NMR, 13 C NMR, mass spectroscopy, and elemental analysis. The as-synthesized compounds were screened for larvicidal and antifeedant activities. The larvicidal activity was evaluated using the mosquito species Culex quinquefasciatus , and the antifeedant activity was evaluated using the fishes of Oreochromis mossambicus . The compounds 2a-i demonstrated lethal effects, killing 50% of second instar mosquito larvae when their LD 50 values were 44.17, 34.96, 45.29, 45.28, 75.96, and 28.99 μg mL -1 , respectively. Molecular docking studies were used for analysis based on the binding ability of an odorant binding protein (OBP) of Culex quinquefasciatus with compound 2h (binding energy = -6.12 kcal mol -1 ) and compound 1g (binding energy = -5.79 kcal mol -1 ). Therefore, the proposed target compounds were synthesized via a green method using Cu(ii)-enzyme as a catalyst to give high yield (94%). In biological screening, benzopyran-connected pyrazole (2h) was highly active compared with benzopyran-connected pyrimidine (1a-g) series in terms of larivicidal activity.