Work

On the Mechanism of Random Handedness Generation in the Reactions of Heterocyclic Aldehydes with Diallylboronates

Year: 2025

Type: article

Abstract: The mechanism of generation of products with opposite handedness in the reactions of heterocyclic aldehydes with diallylboronates was studied by NMR experiments and DFT computations. The origin of this unusual phenomenon is a competition between monomeric and dimeric autoinductors that promote the formation of opposite enantiomers. Thus, NMR data suggest that racemic alcohol 3a, upon dimerization, provides almost exclusively the heterochiral dimeric boronate 5a(RS). This corresponds to the computed results predicting strongly exergonic dimerization with ΔΔG298 −6.5 kcal/mol. Dimerization of the chiral boronate 3a (R) with 82% ee yields 5a (RS) in which all available 3a(S) is bound. As a result, 3 species remain in the solution: (1) 5a(RS), producing a newly formed racemic product in the reaction with 1a, (2) 3a(R), reacting with 1a and yielding an R-configured newly formed product, and (3) 5a(RR), yielding selectively S-configured newly formed product according to computations. Taking into account the equilibria existing between monomers and dimers, the system is capable of demonstrating the experimentally observed random handedness of the newly formed product.

Source: Molecules

DOI: 10.3390/molecules31010128

Authors: Oleg Mikhailov, Ilya D. Gridnev

Institutions: Russian Academy of Sciences, N.D. Zelinsky Institute of Organic Chemistry

Language: English

Topic: Asymmetric Synthesis and Catalysis

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,258

Funder: Russian Science Foundation