Triterpene glycosides ofSilphium perfoliatum. IV. Structure of siliphioside C

A passage from deca-1,4,9-triene (I) to (E,E)-dodeca-8,10-dienol (II) in five stages with an overall yield of 23% has been found by the selective transformations of deca-1,4,9-trien-1-yltrimethylsilane. Thus, under mild conditions, by the hydrogenation of (I) with the aid of 9-borabicyclo3.3.1]nonane (9-BBN) followed by oxidation with H₂O₂ (E,E)-deca-6,8-dienol was obtained with a yield of 60%, and this was converted quantitatively into the corresponding tosylate. The ethynylation of the latter with lithium acetylide gave (E,E)-dodecadien-1-yne (III) on a Lindlar catalyst followed by the reaction of the resulting triene with 9-BBN, as described above for (I) led to the desired codlemone (II). The IR, PMR,¹³C NMR, UV, and mass spectra of the compound obtained are discussed.Institute of Chemistry, Bashkir Branch, Academy of Sciences of the USSR, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 514–518, July–August, 1984.