A simple method for resolution of endo-/exo-monoesters of trans-norborn-5-ene-2,3-dicarboxylic acids into their enantiomers.
Separation of optical isomers obtainable from trans-norborn-5-ene-2,3-dicarboxylic acid methyl and tert-butyl monoesters was performed by crystallization of the respective salts prepared with (R)- and (S)-1-phenylethylamine. Starting from racemic endo-monomethyl ester of trans-norborn-5-ene-2,3-dicarboxylic acid, prepared by partial hydrolysis of the cyclopentadiene-dimethyl fumarate adduct, the corresponding (2R,3R)-endo-monoester was isolated in 97% enantiomeric excess (ee) yield after seven repeated crystallizations from tetrachloromethane. Starting from exo-mono-tert-butyl ester of the same acid, prepared by alcoholysis of the cyclopentadiene-maleic anhydride adduct followed by isomerization, (2R,3R)-exo-monoester was isolated in >98% ee yield after four repeated crystallizations from ethanol. Crystallization of the acids from the mother liquor containing (S)-1-phenylethylamine yielded products with inverse stereochemical configuration.
Department of Organic Chemistry, Belarusian State University, Minsk, Belarus.
Vitaly N
VN
Kovalenko
Yurii Yu
YY
Kozyrkov
D001643:Bridged Bicyclo Compounds / Q000737:chemistry; D002625:Chemistry, Organic / Q000379:methods*; D003460:Crystallization; D003998:Dicarboxylic Acids / Q000737:chemistry* / Q000302:isolation & purification; D006536:Heptanes / Q000737:chemistry; D006868:Hydrolysis; D010627:Phenethylamines / Q000737:chemistry; D013237:Stereoisomerism
C504926:(2.2.1)bicyclohept-2-ene; D001643:Bridged Bicyclo Compounds; D003998:Dicarboxylic Acids; D006536:Heptanes; D010627:Phenethylamines
1-phenylethylamine; Diels-Alder reaction; enantiomer separation; norbornene; recrystallization