Daniela Rodrigues Silva, Lucas A. Zeoly, Pascal Vermeeren, Rodrigo A. Cormanich, Trevor A. Hamlin, Célia Fonseca Guerra, Matheus P. Freitas
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Solvent effects on the sodium borohydride reduction of 2-halocyclohexanones
We have investigated the stereoselectivity and reactivity of the sodium borohydride reduction of 2-X-cyclohexanones (X=H, Cl, Br) using a combined approach of competitive experiments and density functional theory calculations. Our results show that the hydride addition proceeds via a late transition state in which the C–H bond is nearly formed, consistent with the mild reducing power of NaBH4. The reaction barrier decreases from the 2-halocyclohexanones to the unsubstituted cyclohexanone, in line with relative reactivities observed in the competitive experiments. Furthermore, we provide a protocol to solve the longstanding issue of properly modelling the axial–equatorial facial selectivity of hydride addition to the carbonyl group substituted with a vicinal polar group. The inclusion of implicit solvation in combination with an explicit solvent molecule is crucial to reproduce the stereoselective formation of the cis product observed experimentally.
期刊介绍:
The Journal of Physical Organic Chemistry is the foremost international journal devoted to the relationship between molecular structure and chemical reactivity in organic systems. It publishes Research Articles, Reviews and Mini Reviews based on research striving to understand the principles governing chemical structures in relation to activity and transformation with physical and mathematical rigor, using results derived from experimental and computational methods. Physical Organic Chemistry is a central and fundamental field with multiple applications in fields such as molecular recognition, supramolecular chemistry, catalysis, photochemistry, biological and material sciences, nanotechnology and surface science.