Active Mandelic Acid Research Articles

ChemInform Abstract: Improved Optical Resolution of (±)‐1,2‐Diphenylethylenediamine.

(±)-1,2-Diphenylethylenediamine (DPEDA) was efficiently resolved by the fractional crystallization of its diastereomeric salts with optically active mandelic acid. 1H-NMR spectrum of N-monoacylated DPEDA with an optically active derivatizing agent showed that DPEDA thus obtained was optically pure.

Improved Optical Resolution of (±)-1,2-Diphenylethylenediamine

Abstract (±)-1,2-Diphenylethylenediamine (DPEDA) was efficiently resolved by the fractional crystallization of its diastereomeric salts with optically active mandelic acid. 1H-NMR spectrum of N-monoacylated DPEDA with an optically active derivatizing agent showed that DPEDA thus obtained was optically pure.

Herstellung, optische Reinheit und Konfiguration der Flecainid‐Enantiomeren

Preparation, Optical Purity and Configuration of the Enantiomers of Flecainide The chiral antiarrhythmic drug flecainide (rac-1) was resolved by fractional crystallization of the diastereomeric salts with optically active mandelic acid. Derivatization with (+)-1-phenylethyl isocyanate and analytical separation of the diastereomers 3 by HPLC on silica gel confirmed the optical purity of the enantiomers. CD-Spectra of the N-chloro derivatives established the absolute configuration: (−)-1 is R-, (+)-1 S-configurated.

Asymmetric synthesis of α-hydroxy carboxylic acids: direct oxidation of chiral amide enolates using 2-sulfonyloxaziridines

The direct oxidation of chiral amide enolates to optically active mandelic acid using 2-sulfonyloxaziridine 1 is described. The diastereoselectivity is counterion dependent.

Preparation and Activity of β-Substituted Acetylcholine Iodides

The enantiometers of (—)- and (+)-acetyl β-ethylcholine iodide were prepared following the resolution of 1-dimethylamino-2-butanol from (+)-tartaric acid and (+)-bromocamphor-sulfonic acid for the (—)- and (+)-isomers, respectively. The absolute configuration of the (—)-enantiomer was determined by the synthesis of (—)-acetyl β-ethylcholine iodide from R(—)-2-hydroxybutyric acid. The optically active acetyl β-phenylcholine iodides were prepared from the optically active mandelic acids. These enantiomers show that the R(—)-isomers have greater affinity for the acetylchohnesterase receptor and that the S(+)-isomers are more potent agonists on guinea pig ileum.

The preparation of optically active 3-aryl-1,4-dioxaspiro[4,5]decanes and their 2-oxo-derivatives; a study of the cotton effects associated with these compounds

A series of optically active mandelic acids has been prepared, including the 3,4-methylenedioxy-, the 3-methoxy-, and the 2-bromo-compounds which do not appear to have been resolved previously. These acids [(Ia–f) and (III)] were converted by the action of cyclohexanone into the corresponding 3-aryl-1,4-dioxaspiro[4,5]decan-2-ones [dioxolanones (IVa–f) and (V)]. Comparisons of the signs of the experimentally observed Cotton effects with those predicted by application of the lactone sector rule give good agreement. The acids were also reduced by aluminium lithium hydride to the corresponding glycols, which yielded when treated with cyclohexanone the 2-aryl-1,4-dioxaspiro[4,5]decanes [dioxolans (Xa, b, and e) and (XI)]. The dioxolan structures provide a skeletal background which shows up more clearly the Cotton effects associated with the lactone keto-group. The changes in o.r.d. characteristics of phenylethylene glycol on successive methylation of the hydroxy-groups were also recorded.

Chromatographic separation of diastereoisomeric esters—II Mandelates and lactates of 2-methylbutanol-1, 3-methylbutanol-2, pentanol-2 and hexanol-2

The racemic alcohols, 2-methylbutanol-l, 3-methylbutanol-2, pentanol-2 and hexanol-2 have been esterified with optically active mandelic or lactic acid, and the resultant mixtures of diastereoisomeric esters separated chromatographically with an optically inactive sulphonated polystyrene resin as the stationary phase and water or dilute aqueous sodium sulphate as the mobile phase. Lactate esters were more easily separated than mandelate esters. The Chromatographic separation of 26 mmole of (+/-)-3-methyl-2-butyl(+)-lactate and subsequent hydrolysis of the fractions containing only the ester of the (+)-alcohol yielded 1-2 mmole of pure 3-methyl-2-butanol.

CCCLXXXVII.—The relationship between the optical rotatory powers and the relative configurations of optically active compounds. Part II. The relative configurations of the optically active mandelic acids and β-phenyl-lactic acids

CCCLXXXVII.—The relationship between the optical rotatory powers and the relative configurations of optically active compounds. Part II. The relative configurations of the optically active mandelic acids and β-phenyl-lactic acids