Enantioselective 1,3-Dipolar Cycloaddition of Azomethine Ylides and Alkenes

Significance

Silver(I)-catalyzed enantioselective 1,3-dipolar cycloaddition (1,3-DC) of azomethine ylides and alkenes has become a useful transformation. Up to four stereogenic centers can be generated in the resulting proline derivatives. The authors reported that the (S)-BINAP-AgSbF₆ complex is an efficient catalyst for the 1,3-DC between azomethine ylides, such as iminoglycinates 2, and electrophilic alkenes, such as maleimides 1 and trans-1,2-bis(phenylsulfonyl)ethylene 4. Good yields and excellent ee values were obtained. The enantioselectivities with this catalyst were significantly higher than those obtained with (S)-BINAP-AgClO₄ as reported previously.