Spirocoleone: Synthese und Charakterisierung von vier diastereomeren Spiro (methylcyclopropan)‐Substrukturen; Revision der Konfiguration an C(12) und C(15) von Coleon P und Derivaten sowie von Coleon‐Z‐Derivaten; Röntgenstrukturanalysen von Lanugon J und weiteren Spirocoleonen

Spirocoleons: Synthesis and Characterization of Four Diastereomeric Spiro (methylcyclopropane) Substructures; Revision of the Configuration at C(12) and C(15) of Coleon P and Derivatives and Coleon‐Z Derivatives; X‐Ray Analysis of Lanugon J and of Further Spirocoleons 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 its 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 (12 R , 13 R , 15 S )‐ and the novel trans ‐type D with (12 R , 13 R , 15 R )‐configuration (Scheme 1) . The structures of the photoproducts 5a ((12 R , 13 R , 15 R )‐lanugon J) and 7a ((12 R , 13 R , 15 S )‐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 (12 R , 13 S , 15 S )‐ and the cis ‐type C with (12 R , 13 S , 15 R )‐configuration. The four diastereomers A‐D , all possessing (12 R )‐configuration, show very similar properties. However, careful comparison of spectral and chiroptical data allow a differentiation, even in the case of functionalization of H 3 C(17). The (12 S )‐counter‐parts could not yet be prepared.