Catalytic Asymmetric 1,3‐Dipolar Cycloadditions of Alkynes with Isatin‐Derived Azomethine Ylides: Enantioselective Synthesis of Spiro[indoline‐3,2′‐pyrrole] Derivatives

The first catalytic asymmetric 1,3‐dipolar cycloadditions of alkynes with isatin‐derived azomethine ylides have been established in the presence of chiral phosphoric acid, affording synthetically and pharmaceutically important spiro[indoline‐3,2′‐pyrroles] with quaternary stereogenic centers in high yields and excellent enantioselectivities (up to 99% yield, >99% ee). This protocol not only represents the first enantioselective 1,3‐dipolar cycloadditions of alkynes with ketone‐derived azomethine ylides, but also provides the first example of an enantioselective construction of spiro‐oxindole‐based 2,5‐dihydropyrrole scaffold. magnified image