Aldol Reactions of Axially Chiral 5-Methyl-2-(o-aryl)imino-3-(o-aryl)-thiazolidine-4-ones.
Axially chiral 5-methyl-2-(o-aryl)imino-3-(o-aryl)-thiazolidine-4-ones have been subjected to aldol reactions with benzaldehyde to produce secondary carbinols which have been found to be separable by HPLC on a chiral stationary phase. Based on the reaction done on a single enantiomer resolved via a chromatographic separation from a racemic mixture of 5-methyl-2-(α-naphthyl)imino-3-(α-naphthyl)-thiazolidine-4-one by HPLC on a chiral stationary phase, the aldol reaction was shown to proceed via an enolate intermediate. The axially chiral enolate of the thiazolidine-4-one was found to shield one face of the heterocyclic ring rendering face selectivity with respect to the enolate. The selectivities observed at C-5 of the ring varied from none to 11.5:1 depending on the size of the ortho substituent. Although the aldol reaction proceeded with a lack of face selectivity with respect to benzaldehyde, recrystallization returned highly diastereomerically enriched products.
Chemistry Department, Bogazici University, Bebek, 34342 İstanbul, Turkey. sule.erol@boun.edu.tr.
Sule
S
Erol Gunal
Chemistry Department, Bogazici University, Bebek, 34342 İstanbul, Turkey. dogan@boun.edu.tr.
Ilknur
I
Dogan
D000447:Aldehydes / Q000737:chemistry*; D001547:Benzaldehydes / Q000138:chemical synthesis / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D013237:Stereoisomerism; D053778:Thiazolidines / Q000138:chemical synthesis / Q000737:chemistry*
D000447:Aldehydes; D001547:Benzaldehydes; D053778:Thiazolidines; C116609:3-hydroxybutanal; C032175:benzaldehyde
aldol reactions of thiazolidine-4-ones; axial chirality; chromatographic separations on a chiral stationary phase