A general palladium and silver co-catalyzed denitrogenative carbonylation of benzotriazoles for the synthesis of benzoxazin-4-ones has been developed. Employing benzotriazoles as easily accessible substrates and Cr(CO) 6 as bench-stable solid carbonyl sources, various benzoxazin-4-ones were synthesized through a ring-opening/denitrogenative/carbonylation cascade processes in moderate to good yields. Notably, this protocol avoids the use of toxic CO gas and special equipment and can also be applied to the late-stage functionalization of substrates derived from the uricosuric agent probenecid.

A new palladium‐catalyzed reductive double carbonylation of nitroarenes with aryl halides for the synthesis of benzoxazin‐4‐ones has been reported. The key to success was the use of Mo(CO)6 as a reductant and bench‐stable solid carbonyl sources. Various aryl iodides, bromides, and trifluoromethanesulfonates are suitable reaction partners and produce corresponding benzoxazin‐4‐one derivatives in moderate to good yields. Preliminary mechanistic studies indicate that nitrosoarene was first generated as the key intermediate through nitro reduction. Remarkably, this method avoids the use of toxic CO gas and is further applied to the late‐stage modification of estrone.