Highly Selective Copper‐Catalyzed Asymmetric [3+2] Cycloaddition of Azomethine Ylides with Acyclic 1,3‐Dienes |
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| Authors: | María González‐Esguevillas Ana Pascual‐Escudero Dr Javier Adrio Prof?Dr Juan C Carretero |
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| Affiliation: | Departamento de Química Orgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco 28049 Madrid (Spain), Fax: (+34)?914973966 |
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| Abstract: | The first examples of the catalytic asymmetric 1,3‐dipolar cycloaddition of azomethine ylides with acyclic activated 1,3‐dienes (and 1,3‐enynes) are described. Under copper catalysis, a selective cycloaddition at the terminal γ,δ‐C?C bond is observed. In addition, depending on the ligand used, either the exo or the endo adduct can be obtained with high selectivity. Under appropriate reaction conditions, the acyclic 1,6‐addition product is detected, suggesting a stepwise mechanism. The resulting C4‐alkenyl‐substituted pyrrolidines are suitable substrates for further access to polycyclic systems, as highlighted by the preparation of hexahydrochromeno4,3‐b]pyrrole and the tetracyclic core of the alkaloid gracilamine. |
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| Keywords: | asymmetric catalysis azomethine ylides copper cycloaddition dienes |
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