Synthesis of methyl dihydrohardwickiate and its C-4 epimer.: Structural amendment of natural crolechinic acid

Reduction of the α,β-unsaturated ester moiety of (+)-methyl hardwickiate with magnesium in methanol afforded methyl (4a S,6 S,8a S,1 R,5 R)-5,6,8a-trimethyl-5-[2′-(3″-oxoyl)-ethyl-perhydro-1-naphthalenyl]-carboxaylate, while reduction with sodium in n-propanol, followed by esterification with diazom...

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Bibliographic Details
Published in:Phytochemistry (Oxford) 2000-04, Vol.53 (8), p.851-854
Main Authors: Costa, Marta, Perles, Elaine C., Fujiwara, Fred Y., Imamura, Paulo M.
Format: Article
Language:English
Subjects:
(+)-Methyl hardwickiate
Biological and medical sciences
Chemical constitution
Crolechinic acid
Diterpenes - chemical synthesis
Diterpenes - chemistry
Fundamental and applied biological sciences. Psychology
Magnesium - chemistry
Magnetic Resonance Spectroscopy
Plant physiology and development
Reduction
Stereochemistry
Stereoisomerism
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Summary:Reduction of the α,β-unsaturated ester moiety of (+)-methyl hardwickiate with magnesium in methanol afforded methyl (4a S,6 S,8a S,1 R,5 R)-5,6,8a-trimethyl-5-[2′-(3″-oxoyl)-ethyl-perhydro-1-naphthalenyl]-carboxaylate, while reduction with sodium in n-propanol, followed by esterification with diazomethane, furnished its C-4 epimer. After comparison of the 1 H - and 13 C -NMR data of these compounds with those reported for crolechinic acid isolated from Croton lechleri, a stereochemical revision for the natural product is suggested.
ISSN:0031-9422
1873-3700
DOI:10.1016/S0031-9422(99)00583-X