A cobalt-catalyzed direct C-H carbonylative reaction of N-(2-(1H-indol-1-yl)phenyl)picolinamides for the synthesis of (NH)-indolo[1,2-a]quinoxalin-6(5H)-one skeletons has been developed. Using benzene-1,3,5-triyl triformate (TFBen) as the CO source and picolinamide as the traceless… Click to show full abstract
A cobalt-catalyzed direct C-H carbonylative reaction of N-(2-(1H-indol-1-yl)phenyl)picolinamides for the synthesis of (NH)-indolo[1,2-a]quinoxalin-6(5H)-one skeletons has been developed. Using benzene-1,3,5-triyl triformate (TFBen) as the CO source and picolinamide as the traceless directing group, various free (NH)-indolo[1,2-a]quinoxalin-6(5H)-ones were obtained in good yields (up to 88%). Additionally, a series of product derivatizations were demonstrated, and the core fragment of PARP-1 inhibitor C can be readily constructed by this protocol.
               
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