Premium
Triterpenoide, 5. Synthese und Strukturaufklärung einiger neuer 18α‐Oleanolsäurederivate
Author(s) -
Zaprutko Lucjusz,
Gzella Andrzej,
Wrzeciono Urszula
Publication year - 1990
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.199019900171
Subject(s) - chemistry , acetic anhydride , hydrolysis , diastereomer , double bond , acetic acid , hydrogen bromide , isopropyl , hydrogen bond , ethanol , stereochemistry , organic chemistry , medicinal chemistry , molecule , catalysis , bromine
Triterpenoids, 5. — Synthesis and Structure Elucidation of Some New 18α‐Oleanolic Acid Derivatives On treatment with hydrogen bromide, 3β‐acetoxy‐11‐oxoolean‐12‐en‐28‐oic acid methyl ester ( 1 ) affords the expected 18α‐diastereomer 2 and the unknown 3‐isopropyl‐11‐oxo‐4‐nor‐18α‐oleana‐3(5),12‐dien‐28‐oic acid methyl ester ( 3 ) as product of a Wagner‐Meerwein rearrangement accompanied by the migration of the new introduced exocyclic double bond. Alkaline hydrolysis of 2 gives the known methyl ester 5 together with the new 3β,11‐dihydroxy‐12‐oxooleana‐9(11),13(18)‐dien‐28‐oic acid methyl ester ( 4 ). The byproducts 3 and 4 can also be obtained by treatment of 5 with acetic anhydride ( 3 ) or KOH/ethanol ( 4 ), respectively. The structure elucidation of 3 and 4 is described. The structure of 4 was confirmed by X‐ray analysis.