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Säurekatalysierte Umlagerung von 9‐Hydroxyfuranoeremophilanen zu Eremophilanlactonen
Author(s) -
Siegenthaler Peter,
Neuenschwander Markus
Publication year - 1996
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19960790609
Subject(s) - chemistry , rhizome , stereochemistry , botany , biology
Acid‐Catalyzed Rearrangement of 9‐Hydroxyfuranoeremophilanes to Eremophilanlactones 9‐Hydroxyfuranoeremophilanes 1–3 are the main components of freshly harvested rhizomes of P. hybridus ( furanopetasin chemovar, Table, Fig. 1 ). They easily and quantitatively rearrange in the presence of traces of acid to give an epimeric mixture of 8‐H‐eremophilanlactones 4–6 (eremophilenolides, Table, Figs. 4 and 5 ). Besides subsequent oxidation (see 4 → 7 ), this is the most important reaction occuring during drying and storage of rhizomes of P. hybridus ( Figs. 1 and 3 ). A reasonable mechanism of the rearrangement is presented, and spectroscopic structure elucidation of 8‐H‐eremophilanlactones is discussed.