Related Experiment Video
Updated: Mar 20, 2026
Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
Stereoselectivity in (Acyloxy)borane-Catalyzed Mukaiyama Aldol Reactions
Joshua M Lee1, Xin Zhang2, Per-Ola Norrby1,3,4
1Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States.
Abstract:
The origin of diastereo- and enantioselectivity in a Lewis acid-catalyzed Mukaiyama aldol reaction is investigated using a combination of dispersion corrected DFT calculations and transition state force fields (TSFF) developed using the quantum guided molecular mechanics (Q2MM) method. The reaction proceeds via a closed transition structure involving a nontraditional hydrogen bond that is 3.3 kJ/mol lower in energy than the corresponding open transition structure. The correct prediction of the diastereoselectivity of a Mukaiyama aldol reaction catalyzed by the conformationally flexible Yamamoto chiral (acyloxy) borane (CAB) requires extensive conformational sampling at the transition structure, which is achieved using a Q2MM-derived TSFF, followed by DFT calculations of the low energy conformational clusters. Finally, a conceptual model for the rationalization of the observed diastereo- and enantioselectivity of the reaction using a closed transition state model is proposed.
More Related Videos
08:56Synthesis of a Borylated Ibuprofen Derivative Through Suzuki Cross-Coupling and Alkene Boracarboxylation Reactions
Published on: November 30, 2022
08:46Regioselective O-Glycosylation of Nucleosides via the Temporary 2',3'-Diol Protection by a Boronic Ester for the Synthesis of Disaccharide Nucleosides
Published on: July 26, 2018
Related Concept Videos
02:36Regioselectivity and Stereochemistry of Hydroboration
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
03:08Hydroboration-Oxidation of Alkenes
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
01:15Acid-Catalyzed Aldol Addition Reaction
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
01:22Reactions of Aldehydes and Ketones: Baeyer–Villiger Oxidation
The carbonyl center is activated by...