Open AccessHoch effiziente, präparative chromatographische Enantiomerentrennung von 2-Phenyl-1,3-dioxin-4-onen an Cellulose-triacetat und Cuprat-Additionen zu β-Hydroxycarbonsäure-Derivaten
Author(s) -
Dieter Seebàch,
Urs Gysel,
J.N. Kinkel
Publication year - 1991
Publication title -
chimia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.387
H-Index - 55
eISSN - 2673-2424
pISSN - 0009-4293
DOI - 10.2533/chimia.1991.114
Subject(s) - chemistry , enantiomer , reagent , halogenation , stereoselectivity , enantiomeric excess , medicinal chemistry , cleavage (geology) , walden inversion , stereochemistry , organic chemistry , catalysis , enantioselective synthesis , geotechnical engineering , fracture (geology) , engineering
The 2-Phenyl-dioxinones 1 and 2 are resolved on cellulose-triacetate columns (medium pressure, eluent MeOH, separation factors α = 2.0–2.3, injection of g amounts). The enantiomerically pure formyl- and acetylacetate derivatives, thus available undergo diastereoselective (97–99% ds) 1,4-additions with CuCl-doped Grignard reagents or with cuprates to give the dioxanones 5,9, and 10. Eventually, 3-hydroxy-carboxylic acids, esters, and O-benzyl-protected acids (6, 8, 11–13) can be prepared with >96% enantiomeric excess; otherwise not readily available derivatives with a tertiary 3-hydroxy group are accessible by this route (see 11, 12). Two peculiar stereoselective reactions are reported: i) the inversion of configuration upon bromination of the dioxinone 2 ((–)-(R)-2 → (+)-(S)-4) and ii) the highly diastereoselective (91% ds) cleavage of the 2-phenyl-dioxanone 10 with D2/Pd-C(→13). Configurational assignments are based on nuclear Overhauser effects (NOE) and on chemical correlations.