Ashok V. Bhatia

A practical, large-scale procedure for the preparation of N-protected α-amino ketones from α-amino acids

Abstract A convenient multigram-scale method has been developed for the preparation of chiral N-protected α-amino ketones from chiral N-protected amino acids. Several examples using this procedure are reported, including a large scale application.

SYNTHESIS OF 5,6-METHYLENEDIOXY-1-TETRALONE. AN ARYL GRIGNARD APPROACH FROM GUAIACOL

A convenient synthesis of 5,6-methylenedioxy-1-tetralone (1) is described. The main features of this synthesis are the formation of 6 via a Grignard reaction using succinic anhydride followed by selective reduction and Friedel-Crafts cyclization to generate the desired tetralone 1.

Solution conformations of the 6α and 6β epimers of oxymorphamine

Abstract High field (360 MHz) 1 H NMR studies have shown that the conformation of ring C in the oxymorphamines is dramatically influenced by the stereochemistry of the 6-amino group: ring C exists in a chair conformation in the 6β-epimer but adopts a twist boat conformation in the 6α-epimer.

HPLC Separation of the Diastereomeric Glutathione Adducts of Styrene Oxide

Abstract The four diastereomeric thioether adducts resulting from the addition of glutathione to racemic styrene oxide were separated on a Radial Pak C18 column using pH 7 Tris-phosphate buffer solution containing methanol as eluent. The benzylic thioether (1) eluted earlier than the benzylic alcohol (2) regioisomers. A complete stereochemical profile was established with the first eluting stereoisomer assigned as (S,R)-1, followed by (R,R)-1, (S,R)-2, and (R,R)-2,. The diastereomers with S configuration at the benzylic carbon emerged first for each set of regioisomers. The use of glutathione as a chiral probe for the analysis of enantiomerically enriched epoxides was illustrated with β-methylstyrene oxide formed from (1R, 2S)-N,N-dimethylephedrium bromide during the course of a chiral phase-transfer synthesis of oxiranes.

Separation of D and L enantiomers of [(phenylsulfonyl)amino]-3-oxo-1-octadecanol by chiral high performance liquid chromatography

A convenient and rapid method has been developed for the separation of the D and L enantiomers of [(phenyl-sulfonyl)amino]-3-oxo-octadecanol using chiral High Performance Liquid Chromatography (HPLC). An amylose tris(3,5-dimethylphenylcarbamate) chiral HPLC column was used for the separation. The two enantiomers were fully resolved from each other with approximate retention times of 11 and 13 minutes for the L and the D forms respectively. The total run time per sample was 30 minutes.