Racemization mechanism of lithium tert‐butylphenylphosphido‐borane: A kinetic insight

• Published in: Chirality (New York, N.Y.) Vol. 34; no. 1; pp. 27 - 33
• Main Authors: Fortrie, Rémy, Gatineau, David, Hérault, Damien, Béal, Aurélie, Naubron, Jean‐Valère, Giordano, Laurent, Buono, Gérard
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01-01-2022; Wiley
• Subjects: Boranes; Chemical Sciences; chiral ligand; complex reaction scheme analysis; Convergence; DFT modeling; kinetic modeling; kinetic resolution; Kinetics; Lithium; Phosphides; Racemization; Stereoisomerism; kinetic resolution; complex reaction scheme analysis; chiral ligand; DFT modeling; kinetic modeling
• ISSN: 0899-0042; 1520-636X
• DOI: 10.1002/chir.23383

The racemization mechanism of tert‐butylphenylphosphido‐borane is investigated experimentally and theoretically. Based on this converging approach, it is shown, first, that several phosphido‐borane molecular species coexist at the time of the reaction and, second, that one particular of both initially assumed reactive routes most significantly contribute to the overall racemization process. From our converging modeling and experimental measurement, it comes out that the most probable species to be here encountered is a phosphido‐borane‐Li (THF)2 neutral solvate, whose P‐stereogenic center monomolecular inversion through a Y‐shaped transition structure (ΔrG°≠: 81 kJ mol−1) brings the largest contribution to the racemization process.
Experimental and theoretical investigations of lithium phosphido‐borane racemization kinetic.