An expeditious synthesis and anticancer activity of novel 4-(3'-indolyl)oxazoles

A series of 4-(3'-indolyl)oxazole congeners have been synthesized and studied for their cytotoxicity against six cancer cell lines. Reaction of 3-acetyl-1'-benzenesulfonylindole with [hydroxy(tosyloxy)iodo]benzene afforded pure 3-tosyloxyacetyl-1'-benzenesulfonylindole. Microwave-accelerated neat reaction of 3-tosyloxyacetyl-1-benzenesulfonylindole with amides resulted in the exclusive formation of 4-(1'-benzenesulfonylindol-3'-yl)-2-substituted oxazoles (4) in very good yield. Treatment of 4 with aqueous sodium hydroxide under refluxing conditions afforded pure 4-(3'-indolyl)-2-substituted oxazoles (5) in excellent yield. The 4-(3'-indolyl)oxazoles 5d and 11 were found to be most cytotoxic and selective against various cancer cell lines. Compounds 5g, 5j and 5l showed moderate anticancer activity.