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Limbetazulone: a New ‘Decahydro‐8‐oxanaphtho[2,1‐ f ]azulen‐7‐one’ Diterpenoid from Ballota limbeta , and Occurence of Two Conformational Isomers in the Crystal
Author(s) -
Riaz Muhammad,
Krohn Karsten,
Malik Abdul,
Flörke Ulrich
Publication year - 2004
Publication title -
chemistry and biodiversity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 70
eISSN - 1612-1880
pISSN - 1612-1872
DOI - 10.1002/cbdv.200490038
Subject(s) - chemistry , furan , azulene , hydroxymethyl , terpenoid , stereochemistry , crystal structure , crystallography , organic chemistry
A new diterpenoid, limbetazulone (=(3 S ,4 S ,4a R ,12b S )‐1,2,3,4,4a,5,6,11,12,12b‐decahydro‐3‐hydroxy‐4‐ (hydroxymethyl)naphtho[1′,2′: 5,6]cyclohepta[1,2‐ b ]furan‐7(7 H )‐one; 1 ), with the very rare ‘naphtho[2,1‐ f ]azulene‐7‐one’ skeleton, was isolated from the aerial parts of the Asian medicinal plant Ballota limbeta. Its structure was established by extensive spectroscopic investigations, especially 1D and 2D NMR. X‐Ray diffraction studies showed the presence of two conformational isomers ( 1a and 1b ) in the crystal.