Three‐Component [2+2+1] Gold(I)‐Catalyzed Oxidative Generation of Fully Substituted 1,3‐Oxazoles Involving Internal Alkynes

Abstract Three‐component [2+2+1] gold(I)‐catalyzed reaction of internal alkynes (alkynyl esters or ‐ketones), nitriles, and 2‐chloropyridine N ‐oxide led to a wide range of fully substituted 1,3‐oxazoles (32 examples; up to 92% isolated yields). Nitrile R 3 CN species, employed in the reaction as both reactants and solvents, comprise conventional nitriles (R 3 =Alk, Ar) and also push‐pull systems such as cyanamides (R 3 =NH 2 and NAlk 2 ) and the thiocyanate (R 3 =SPr). The advantages of the developed method include mild reaction conditions, high functional‐group tolerance, broad range of substituents R 1 /R 3 along with a possibility of easy modification of COR 2 or the amino group when R 1 =NH 2 . magnified image