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Carbohydrate‐Derived 3,2‐Enolones in the Base‐Catalyzed Rearrangement to Highly Functionalized C 4‐Quaternary 4‐Hydroxy‐2‐cyclopentenones
Author(s) -
Borowski Daniel,
Oechsner Regina M.,
Jürgens Eva,
Ziegler Thomas
Publication year - 2017
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201700846
Subject(s) - chemistry , stereocenter , isomerization , dihydropyran , medicinal chemistry , solvent , carbohydrate , stereochemistry , organic chemistry , catalysis , enantioselective synthesis
3,4,6‐ O ‐benzylated β‐2‐ulosides were subjected to 3,4‐elimination, providing carbohydrate‐derived 3,2‐enolones. Reaction of these enolones under basic conditions in polar aprotic solvents afforded highly functionalized racemic 5‐alkoxy‐2‐benzyloxy‐4‐benzyloxymethyl‐4‐hydroxy‐2‐cyclopentenones. The influence of the nature of the base as well as solvent effects were investigated. The rearrangement products obtained from this reaction exhibit a 4‐hydroxy‐ C 4‐quaternary stereogenic center. In contrast, the rearrangement of comparable dihydropyran‐3‐ones was reported to furnish the C 5‐quaternary 5‐hydroxy‐2‐cyclopentenones. Plausible mechanisms for the described rearrangement and subsequent isomerization processes are given.