Diastereoselective Aldol Reaction of 7-Bromo-5- pyrido-1,4-benzodiazepin-2-one; Relative and Absolute Configuration of All Stereoisomers (CROSBI ID 92976)
Prilog u časopisu | izvorni znanstveni rad | međunarodna recenzija
Podaci o odgovornosti
Majerić-Elenkov, Maja ; Žiher, Dinko ; Višnjevac, Aleksandar ; Hameršak, Zdenko ; Kojic-Prodic, Biserka ; Šunjic, Vitomir
engleski
Diastereoselective Aldol Reaction of 7-Bromo-5- pyrido-1,4-benzodiazepin-2-one; Relative and Absolute Configuration of All Stereoisomers
Aldol reaction of C(3) carbanion of 7-bromo-5-pyrido- 1, 4-benzodiazepin-2-one (1) with representative aliphatic and aromatic aldehydes and ketones afforded racemic mixtures syn/anti-7-bromo-3-(1˘-hydroxy-1˘- phenylmethyl)-1-methyl-5-(2'-pyridyl)-2, 3-dihydro-1H- 1, 4-benzodiazepin-2-one (2/3), syn/anti-7-bromo-3- (1˘-hydroxy-1˘-phenylmethyl)-1-methyl-5-(2'- pyridyl)-2, 3-dihydro-1H-1, 4-benzodiazepin-2-one (4/5) and syn/anti-7-bromo-3-(1˘-hydroxy-2˘-methylethyl)-1- methyl-5-(2'-pyridyl)-2, 3-dihydro-1H-1, 4- benzodiazepin-2-one (6/7) with 60-85% diastereoselectivity. For prevailing diastereomeric racemates (ą)-2 and (ą)-4 syn relative configuration is deduced, whereas prevailing diastereomer (ą)-7 has anti configuration. Configurational assignment is based on 1H-NMR data and X-ray structure analysis, and the origin of inversion of diastereoselectivity is discussed. Racemic mixtures are separated on chiral HPLC column, and on the bases of the CD spectra (3R) absolute configuration is determined for (+)-enantiomers, and (3S) configuration for (-)- enantiomers. Consequently, (3R, 1˘S) configuration is assigned to syn-(+)-enantiomers and (3R, 1˘R)- configuration to anti-(+)-enantiomers. In an attempt to use enantiomerically pure compounds 2-7 as catalysts in asymmetric alkylation of benzaldehyde by diethyl zinc, these ligands proved chemically and configurationally unstable.
1 ; 4-benzodiazepines ; Enantioseparation ; Hplc chiral chromatography ; Relative and absolute configuration
nije evidentirano
nije evidentirano
nije evidentirano
nije evidentirano
nije evidentirano
nije evidentirano