Abstract
New chiral bipyridyl alcohols and the corresponding N,N-dioxide derivatives were obtained with high enantiomeric excess by a chemo-enzymatic procedure. Metalation of commercial 6,6’-dimethyl-2,2’-bipyridine followed by reaction with acetaldehyde furnished an inseparable 1:1 mixture of dl- and meso- 6,6’-bis(2-hydroxypropyl)-2,2’-bipyridine ((±)-7a and meso-7b) that was subjected to lipasecatalysed enantioselective esterification with vinyl acetate in organic solvent. Immobilised Mucor Miehei lipase (Lipozyme® IM) displayed high stereoselectivity and unreacted alcohol (S,S)-7a, monoacetyl derivative (R,S)-6 and diacetate (R,R)-9 were obtained in high optical purities as the result of the simultaneous resolution of the racemate and desymmetrization of meso isomer. After separation, the chiral compounds were converted into the corresponding N,N-dioxide derivatives with additional axial chirality stereoselectively induced during the N,N-oxidation and some considerations about their stereochemistry and atropisomeric stability were deduced by circular dichroism spectroscopy.
Keywords: Atropoisomers, Bipyridine, Circular Dichroism, Esterification, Lipase, N, N-oxidation, stereogenic, monoacetate, bipyridines, atropisomerism
Related Books
2-Deoxy-D-Glucose: Chemistry and Biology
Chiral Ionic Liquids: Applications in Chemistry and Technology
Basics of Organic Chemistry: A Textbook for Undergraduate Students
Advances in Organic Synthesis
The Synthetic Methods, Structures, and Properties of the Ca-C σ Bond Organocalcium Containing Compounds
Advances in Organic Synthesis
Chemistry of Bipyrazoles: Synthesis and Applications
Advances in Organic Synthesis
Advanced Nanocatalysis for Organic Synthesis and Electroanalysis
Advances in Organic Synthesis
12