Regioselective [3 + 2] Cycloaddition Between Ynamides and Pyridine‐<i>N</i>‐Aminides Catalyzed by PicAuCl₂ Anchored Onto SBA‐15

ABSTRACT A dichloro(2‐pyridinecarboxylato)gold complex anchored on SBA‐15 (SBA‐15‐PicAuCl 2 ) was conveniently prepared through the addition reaction between triethoxy(3‐isocyanatopropyl)silane and dichloro(3‐hydroxy‐2‐pyridinecarboxylato)gold complex and subsequent condensation with SBA‐15. The new heterogenized PicAuCl 2 complex was fully characterized by using various analytic methods. In the existence of 5 mol% of SBA‐15‐PicAuCl 2 , the regioselective [3 + 2] cycloaddition reaction between ynamides and pyridine‐ N ‐aminides proceeded in toluene at 100°C for 1–24 h to deliver a wide array of functionalized trisubstituted 1,3‐oxazoles in 57%–95% yields. Ynamides with alkyl, benzyl, and aryl substituents as well as different sulfonyl groups at the nitrogen atom and the oxazolidinone‐derived ynamides were well‐tolerated. A wide range of pyridine‐ N ‐aminides bearing aroyl, naphthoyl, furoyl, vinylcarbonyl, alkylcarbonyl, and methoxycarbonyl were also allowed in the reaction. Moreover, SBA‐15‐PicAuCl 2 is easy to recover through a simple centrifugation and recyclable at least seven cycles with only a slight drop in catalytic activity.