StatusThe thesis was presented on the 8 November, 2007
Approved by NCAA on the 20 December, 2007
Abstract– 0.39 Mb / in romanian
– 0.39 Mb / in russian
ThesisCZU 547.596/599 0.86 Mb / in russian
The present thesis is devoted to the elaboration of the synthetic methods of specifically functionalized aliphatic terpenoids and the study of the regularities of their superacidic cyclization. The work represents the basic as well as practical interest, because it opens efficient ways to less accessible compounds which are difficult to prepare by other means.
The synthesis of methyl (2Z,6Z,10E,14E)- and (2E,6Z,10E,14E)- geranylfarnesoates was accomplished and their superacidic cyclization was studied. It was demonstrated that the presence of (6Z)-double bond in these compounds led to mixtures of scalaranic, heilanthanic and rearranged heilanthanic derivatives. The presence of (6Z)-double bond in starting compounds makes them similar with natural polyprenols and simulates the biogenetic transformation of pentaprenol into cyclic compounds.
Two synthetic variants were elaborated for the preparation of the natural bioactive diol 16-hydroxy-all trans-geranylgeraniol and a range of its derivatives. It was shown that the superacidic cyclization of 16-acetoxy-all trans-geranylgeraniol represents an efficient original synthesis of sacculatanic diterpenoids. These diterpenoids possess biological activity but are less accessible, because their preparation by other ways is rather difficult.
The synthesis of the THP-ether of all-trans-8-phenylsulfonylgeranylfarnesol was accomplished. Its superacidic treatment led to the THP-ether of (13E,17E)-∆8- bicyclo-12-phenylsulfonylgeranylfarnesol. It was demonstrated that the phenylsulfonyl group had deactivated the allylic double bond and stoped the cyclization process. By introduction of this functional group into a suitable place of polyenic chain it is possible to run selectively the cyclization process. The optically active (13E,17E)-∆8-bicyclo-12-phenylsulfonylgeranylfarnesol was prepared starting with norambreinolide.
The reaction of superacidic cyclization in ionic liquids was effectuated for
the first time on the example of sesquiterpenic compounds. It was shown that the
reaction gives good result only in the case of compounds with functional groups
resistant to acidic medium (COOH, COOR, PhSO2).