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Derailed Ohira-Bestmann Reaction of γ,δ-Unsaturated Aldehydes for the Stereoselective Synthesis of Cyclopenta[c]pyrazoles |
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| Authors: | Tobias Sandmeier Niels Sievertsen Erick M Carreira |
| Institution: | 1. Laboratorium für Organische Chemie, Department of Chemistry and Applied Biosciences, ETH-Zürich, CH-8093 Zürich, Switzerland
These authors have contributed equally to the work.;2. Laboratorium für Organische Chemie, Department of Chemistry and Applied Biosciences, ETH-Zürich, CH-8093 Zürich, Switzerland |
| Abstract: | The synthesis of cyclopentac]pyrazoles from γ,δ-unsaturated aldehydes by a domino sequence involving one-carbon homologation and intramolecular azomethine imine 1,3-dipolar cycloaddition is disclosed. The fused pyrazoles bearing aromatic and aliphatic substituents are obtained in good yields and excellent diastereomeric purity. Additionally, the synthetic utility of the pyrazole products generated by this method has been highlighted in a series of functionalization reactions. The method presented opens strategic opportunities for the synthesis of pyrazole-containing biologically active compounds. |
| Keywords: | pyrazoles cycloaddition reactions homologation domino reactions cascade reactions Ohira-Bestmann reaction |