Synthesis and biological significance of pyrano pyrazoles from 8,9-dimethyl-3- acetoacetyl pyrano[3,2-c ][1 ]benzopyran-2,5-dione

Department of Chemistry, Aligarh Muslim University, Aligarh-202 002, Uttar Pradesh, India

E-mail: siddiqui_zeba@yahoo.co.in

Manuscript received 6 August 2008, revised 13 April 2009, accepted 4 September 2009

6,7-Dimethyl-3-formyl-4-hydroxycoumarln 1 was treated with triacetic acid lactone 2 in heating methanol to afford 8,9-dlmethyl-3-acetoacetyl pyrano[3,2-c][l]benzopyran-2,5-dione 3. The compound 3 was transformed to pyrano pyrazole derivatives 4a-c by treatment with nitrogen bases such as hydrazine hydrate, phenylhydrazine and hydrazinobenzothiazole. The structure of all compounds was established on the basis of spectroscopic studies and screened for their antibacterial and anti-inflammatory activities.