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

• Published in: Tetrahedron Vol. 50; no. 16; pp. 4623 - 4634
• Main Authors: Kodukulla, Ram Prasad K., Hariharan, S., Trivedi, Girish K.
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 18.04.1994; Elsevier
• Subjects: 3-Nitro-2-phenyl-2H-1-benzopyrans; Antimicrobial; Benzopyranopyrazole; Benzopyranopyrazoline; Chemistry; Chemistry, Organic; Cycloaddition; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with n hetero atom and also o and/or s, se, te hetero atoms; Organic chemistry; Physical Sciences; Preparations and properties; Science & Technology; Antimicrobial; Cycloaddition; 3-Nitro-2-phenyl-2H-1-benzopyrans; Benzopyranopyrazole; Benzopyranopyrazoline; CYCLOADDITION; 3-NITRO-2-PHENYL-2H-1-BENZOPYRANS; 3,5-DIPHENYL-1H-PYRAZOLE DERIVATIVES; ANTIMICROBIAL; BENZOPYRANOPYRAZOLE; AGENTS; BENZOPYRANOPYRAZOLINE; ADDITIONS; Stereoselectivity; Nitro compound; 1,3-Dipolar cycloaddition; Bicyclic compound; Aromatic compound; Tricyclic compound; Oxygen heterocycle; Biological activity; Antimicrobial agent; Oxygen nitrogen heterocycle
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/S0040-4020(01)85003-1

Reactions of diazoalkanes with 3-nitro-2-phenyl-2H-1-benzopyrans lead to the corresponding benzopyranopyrazoles instead of the C-alkylated, ring expansion and ring contraction products as observed with 3-nitrochromones and 3-nitrocoumarins. 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.