Stereoselective Csp3–Csp2 Bond‐Forming Reactions by Transition‐Metal‐Free Reductive Coupling of Cyclic Tosylhydrazones with Boronic Acids |
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| Authors: | Manuel Plaza Dr M Carmen Pérez‐Aguilar Dr Carlos Valdés |
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| Affiliation: | Departamento de Química Orgánica e Inorgánica and Instituto Universitario de Química Organometálica “Enrique Moles”, Universidad de Oviedo, Oviedo, Spain |
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| Abstract: | The reactions between alkenylboronic acids and tosylhydrazones derived from substituted cyclohexanones lead to the construction of disubstituted cyclohexanes with total regio‐ and stereoselectivity. In these transition‐metal‐free processes, a Csp3?Csp2 and Csp3?H bond are formed on the same carbon atom. The stereoselective reaction is general for 2‐, 3‐, and 4‐substituted cyclohexanone tosylhydrazones, as well as for 2‐substituted cyclopentanones. However, no stereoselectivity is observed for acyclic derivatives. DFT computational modeling suggests that the stereoselectivity of the reaction is determined by the approach of the boronic acid to the diazocyclohexane on its most stable chair conformation through an equatorial trajectory. |
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| Keywords: | boronic acids diazo compounds reductive coupling stereoselectivity tosylhydrazones |
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