Allylboration of Ketones Catalyzed by BINOL Derivatives: Which Species Are Involved Depending on Substrate Reactivity?
Résumé
Allylboration reactions of ketones catalyzed by BINOL derivatives can exhibit highly variable stereochemical courses depending on the nature and reactivity of the ketone substrate. In this article we put into perspective the relationship between the nature of the starting material and the active species involved in the asymmetric allyboration catalyzed by BINOL derivatives. This work, aimed at comparing different plausible mechanisms by DFT at M06-2X/6-311+G(d,p) level, involving different types of allylboronates in the presence of the organocatalyst, leads to the confirmation of the hitherto accepted hypothesis of a reaction promoted by the transient cyclic allyl-1,3,2-dioxaborolane derived from BINOLs in the case of unactivated or weakly activated ketones such as indanone. A hypothetical scenario involving dimeric boronate species as chiral catalysts was also investigated.
Domaines
Chimie organiqueLicence |
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