Synthesis and antimicrobial activity of novel 4H-pyrano[2,3-f]indole derivatives

5-Hydroxyindoles 1a-b have been subjected to regioselective Friedel-Craft's acetylation to secure 3,6-diacetyl-5-hydroxyindoles 2a-b which on condensa tion with benzoic acids by using pyridine and phosphorous oxychloride furni sh the required esters 3a-f in good yields. These eaters 3a-f are subjected to Baker-Venkataraman transformations to obtain 3-acetyl-6-benzoylacetyl-5 -hydroxyindoles 4a-f which are refluxed in AcOH and cone. HCl to afford the novel 2-phenyl-4H-pyrano[2,3-f]indol-4-one derivatives 5a-f. Similarly whe n 4a-f are heated with Ac2O and AcONa new 2-methyl-3-benzoyl-4H-pyrano[2,3f ]indol-4-one derivatives 6a-f are obtained. All these new compounds have be en screened for their antibacterial and antifungal activities.