AN IMPROVED LARGE-SCALE SYNTHESIS OF BENZ[CD]INDOL-2(1H)-ONE AND 5-METHYLBENZ[CD]INDOL-2(1H)-ONE

An improved synthesis of benz[cd]indol-2(1H)-one (3) and a novel synth esis of 5-methylbenz[cd]indol-2(1H)-one (4) utilizing analogous method ology is reported, Starting from 1,8-naphthoic anhydride and 4-nitro-1 ,8-naphthoic anhydride, an appropriately substituted N-(2,4-dinitrophe noxy)naphthalimide is prepared. Subjecting these intermediates to impr oved Lossen rearrangement conditions yields 3 and 5-nitrobenz[cd]indol -2(1H)-one (11). 11 is converted to 5-iodobenz[cd]indol-2(1H)-one (13) by standard reduction and diazonium chemistry. 13 is converted to 4 b y palladium(II)-catalyzed coupling of the aryl iodide with methyl-Grig nard.