Simple and efficient methods for discrimination of chiral diacids and chiral alpha-methyl amines.
The three-component chiral derivatization protocols have been developed for (1)H, (13)C and (19)F NMR spectroscopic discrimination of chiral diacids by their coordination and self-assembly with optically active (R)-α-methylbenzylamine and 2-formylphenylboronic acid or 3-fluoro-2-formylmethylboronic acid. These protocols yield a mixture of diastereomeric imino-boronate esters which are identified by the well-resolved diastereotopic peaks with significant chemical shift differences ranging up to 0.6 and 2.1 ppm in their corresponding (1)H and (19)F NMR spectra, without any racemization or kinetic resolution, thereby enabling the determination of enantiopurity. A protocol has also been developed for discrimination of chiral alpha-methyl amines, using optically pure trans-1,2-cyclohexanedicarboxylic acid in combination with 2-formylphenylboronic acid or 3-fluoro-2-fluoromethylboronic acid. The proposed strategies have been demonstrated on large number of chiral diacids and chiral alpha-methyl amines.
NMR Research Center and Solid State and Structural Chemistry Unit Indian Institute of Science, Bangalore-560012, India.
Sachin R
SR
Chaudhari
N
N
Suryaprakash
D001547:Benzaldehydes / Q000737:chemistry; D001897:Boronic Acids / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry*; D003509:Cyclohexanecarboxylic Acids / Q000737:chemistry; D003998:Dicarboxylic Acids / Q000737:chemistry; D004952:Esters / Q000737:chemistry; D054879:Halogenation; D009682:Magnetic Resonance Spectroscopy / Q000191:economics / Q000379:methods*; D008744:Methylamines / Q000737:chemistry*; D010627:Phenethylamines / Q000737:chemistry; D013237:Stereoisomerism
C532809:2-formylphenylboronic acid; D001547:Benzaldehydes; D001897:Boronic Acids; D002264:Carboxylic Acids; D003509:Cyclohexanecarboxylic Acids; D003998:Dicarboxylic Acids; D004952:Esters; D008744:Methylamines; D010627:Phenethylamines; C534517:cyclohexane-1,2-dicarboxylic acid; C033198:1-phenethylamine