84808-15-1Relevant academic research and scientific papers
The Stereochemistry of the Nucleophilic Opening of the Cyclopropane Ring in the four Diastereomeric Lanugons J (Spirocoleons)
Buss, Peter,Prewo, Roland,Bieri, Jost. H.,Rueedi, Peter
, p. 456 - 466 (2007/10/02)
Methanolysis of the spiro(methylcyclopropane) moiety in the four diastereomeric 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.
37. Spirocoleone: Synthese und Characterisierung von vier diastereomeren Spiro(methylcyclopropan)-Substructuren; Revision der Konfiguration an C(12) und C(15) von Coleon P und Derivaten sowie von Coleon-Z-Derivaten; Roetgenstructuranalysen von Lanugon J und weiteren Spirocoleonen
Rueedi, Peter,Schmid, Jean Martin,Prewo, Roland,Bieri, Jost Hans,Eugster, Conrad Hans
, p. 429 - 449 (2007/10/02)
X-ray analyses show the correctness of the previously published structure of coleon Q (1), establish the structure of lanugon J (4a), and necessitate a revision of the configuration at C(12) and C(15) in coleon P (3a) and ist derivatives 3b and 3c, and furthermore of the coleon Z derivatives 11a-11d.Two further diastereomeric spiro(methylcyclopropane) substructures have been generated by photoisomerization of lanugon J (4a) and 12-O-desacetylcoleon N (8); they represent the novel cis-type B with (12R, 13R, 15S)- and the novel trans-type D with (12R, 13R, 15R)-configuration (Scheme 1).The structures of the photoproducts 5a ((12R, 13R, 15R)-lanugon J) and 7a ((12R, 13R, 15S)-lanugon J) were established by X-ray analysis.So far, only two of the eight possible diastereomers of the spiro(methylcyclopropane) substructure I have been detected in nature, i.e. the trans-type A with (12R, 13S, 15S)- and the cis-type C with (12R, 13S, 15R)-configuration.The four diastereomers A-D, all possessing (12R)-configuration, show very similar properties.However, careful comparison of spectral and chiroptical data allow a differentiation, even in the case of functionalization of H3C(17).The (12S)-counterparts could not yet prepared.
