A K₂CO₃‐Mediated Regioselective Synthesis of Indole/Pyrrole‐Fused 1,4‐Oxazines: An Unexpected Indole‐Fused Azlactone Synthesis

Abstract

Abstract A highly regioselective and efficient base‐catalyzed intramolecular hydroalkoxylation of primary and secondary alkynyl alcohols was developed to afford 1,4‐oxaza heterocycles. Although the rates of cyclization for terminal alkynyl alcohols were significantly greater than those for internal ones, our method tolerated both terminal and internal alkynes. In addition, an unprecedented one‐pot hydroamination reaction was found to proceed with high chemo‐ and regioselectivity to form indole‐fused azlactones in the presence of base.