Chemoenzymatic synthesis of chiral unsymmetrical benzoin esters

• Published in: Tetrahedron 2011-09, Vol.67 (38), p.7321-7329
• Main Authors: Hoyos, Pilar, Pace, Vittorio, Sinisterra, José V., Alcántara, Andrés R.
• Format: Article
• Language: English
• Subjects: Benzoin; Benzoins; Bioconversions. Hemisynthesis; Biological and medical sciences; Biotechnology; Catalysis; Catalysts: preparations and properties; Chemistry; Dynamic kinetic resolution; Enantioselectivity; Esters; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General and physical chemistry; Lipase; Methods. Procedures. Technologies; Noncondensed benzenic compounds; Organic chemistry; Phenyls; Preparations and properties; Pseudomonas; Racemization; Regioselectivity; Synthesis (chemistry); Tetrahedrons; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/j.tet.2011.07.030

A chemoenzymatic Dynamic Kinetic Resolution (DKR) of unsymmetrical benzoins (Ar 1≠Ar 2) has been carried out, by using Pseudomonas stutzeri lipase stereorecognition pattern. After studying this lipase behaviour, a high preference towards acylation of those benzoins containing substituents in the phenyl ring rather than in the benzoyl moiety was observed. This fact allowed the development of the DKR process of this kind of substrates, avoiding the accumulation of secondary products derived from the in situ racemization mediated by Shvo’s catalyst action, and allowing the synthesis of enantiopure unsymmetrical benzoins acetates (not previously described) in very good yields (60–95%) and excellent enantiomeric excess values (always >99%). [Display omitted]