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