Stereochemical Investigation in the 1,3‐Dipolar Cycloadditions of 3‐ Nitro‐2‐phenyl‐2H‐1‐benzopyrans to Diazoalkanes: Synthesis and Antimicrobial Activity of Novel Benzopyranopyrazole Derivatives.

TLDR: A series of 3-nitro-2-phenyl-2H-1-benzopyrans (3a-h) were prepared and treated with diazomethane and diazoethane to give various benzopyranopyrazole derivatives as discussed by the authors.

Abstract: A series of 3-nitro-2-phenyl-2H-1-benzopyrans (3a-h) were prepared and treated with diazomethane and diazoethane to give various benzopyranopyrazole derivatives namely [1,9-b]dihydro-3a- nitro-4-phenyl[1]benzopyrano[3,4-c]pyrazolines(4a-h), 4-phenyl[1]benzopyrano [3,4-c]pyrazoles (5a-h) and [1,9-b]dihydro-1-methyl-3a-nitro-4-phenyl[1]benzopyrano[3,4-c]pyrazolines (6a-h) respectively. The regio and stereochemical outcome of these cycloadditions are discussed. The benzopyranopyrazole derivatives 4a-h and 6-ah were tested for their antimicrobial activities against S. aureus, S. lutea, B. subtilis, E. coli, S. typhosa, S. cerevesciae and C. albicans. Compounds 4a-h were found to be moderately active against the gram positive bacteria and the fungi that were tested.