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Gezielte Funktionalisierung des Pimarangerüstes, II. Aufbau des D‐Ringes zur Synthese höherer Terpene
Author(s) -
John Michael,
Haslinger Ernst
Publication year - 1992
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.1992199201168
Subject(s) - chemistry , terpene , ring (chemistry) , stereochemistry , stereoselectivity , double bond , decarboxylation , alkylation , biomimetic synthesis , organic chemistry , catalysis
Directed Functionalization of the Pimarane Skeleton, II. — Formation of the D‐Ring for the Synthesis of Higher Terpenes The conversion of the pimarane skeleton 1 into the tetracyclic compound 3 is described. The synthetic route includes the formation of the D‐ring and the stereoselective introduction of an angular methyl group at C‐14. D‐ring construction has been achieved by selective oxidation of the double bond systems of 2 which lead via 14 to compound 18 . This was alkylated to 19 and subsequently converted into 20 . Further oxidation gave 21 and the ester 24 which upon treatment with potassium tert ‐butoxide formed 25 . The angular methyl group was introduced using a organocopper ragent: 26 . After decarboxylation and hydrogenation 3 was obtained. It can be used as building unit for the construction of higher terpenes (e.g., tirucallanes 4 ).