| Popis: |
Catalytic addition of chiral phosphine, that is, (R)- or (S)-SITCP, to an α-substituted allene ester generated a zwitterionic dipole. Under optimized reaction conditions, this dipole could engage isatine-derived N-Boc-ketimines in a novel mode of [3+2] annulation reaction. Pyrrolinyl spirooxindoles are thus afforded in high yields and with excellent enantioselectivities. The unprecedented annulation reaction successfully facilitated the construction of sp(3) -rich and highly substituted 3,2'-pyrrolidinyl spirooxindoles supporting many chiral centers. |
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