Chemoselective Cyclodehydration of α‐Acyl‐β‐arylaminoacrylamides Using Hendrickson Reagent: Access to Polysubstituted 4‐Aminoquinolines and Diazaphenacenes

Abstract A chemoselecive cyclodehydration of α ‐acyl‐ β ‐arylaminoacrylamides via an electrophilic activation strategy has been described. A series of substituted 4‐aminopyridines are chemoselectively prepared in 73–92% yields from α ‐acyl‐ β ‐arylaminoacrylamides activated by hexaphenyloxodiphosphonium triflate (Hendrickson reagent), whereas substituted diaza[n]phenacenes (n=4–6) are obtained in 72–93% yields directly from α ‐acyl‐ β ‐arylaminoacrylamides using Hendrickson reagent in combination with triflic anhydride (Tf 2 O). The synthetic protocols feature with readily available starting materials, mild reaction conditions, simple execution, and wide range of synthetic potential of products.