ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The Stereochemistry of the Nucleophilie Opening of the Cyclopropane Ring in the four Diastereoisomeric Lanugons J (Spirocoleons)Methanolysis of the spiro(methylcyclopropane) moiety in the four diastereoisomeric lanugons J 3 (13S, 15R), 4 (13R,15R), 5 (13S,15S), and 6 (13R,15S) is shown to proceed stereospecifically with inversion of the configuration at the attacked C-atom (C(15)). The resulting epimeric 2-methoxypropyl-substituted hydroxy-1,4-benzoquinones (royleanones) 7a/8a (monomethoxy derivatives) and 7b/8b (dimethoxy derivatives) could be separated by HPLC using the recently described ‘Non-Aqueous Cation Exchange System’. Respective pairs of 1H-NMR spectra exhibit minute but significant differences in the ABMX3 part of the 2-methoxypropyl group. The final structure assignment is based on a single-crystal X-ray analysis of the dimethoxyroyleanone 7b, whose absolute configuration was established by chiroptical correlation with known abietanoids. Thus, methanolysis of 3 and 4 ((R)-configuration at the reaction centre) yielded the royleanones 7a and 7b with (S)-configuration, whereas analogous treatment of 5 and 6 ((S)-configuration at the reaction centre) led to the corresponding derivatives 8a and 8b both having the (R)-configuration in the 2-methoxypropyl side chain.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19860690227
