Superacid-Catalyzed Cyclization of Methyl (6Z)-Geranylfarnesoates
作者:Marina Grinco、Veaceslav Kulciţki、Nicon Ungur、Wieslaw Jankowski、Tadeusz Chojnacki、Pavel F. Vlad
DOI:10.1002/hlca.200790122
日期:2007.6
Methyl (2Z,6Z,10E,14E)- (3) and methyl (2E,6Z,10E,14E)-geranylfarnesoate (4) were prepared, and then individually cyclized in the presence of the superacid FSO3H. In the case of substrate 3, the scalaranic ester 9 (26%) and the cheilanthanic ester 10 (39%) were isolated. Under the same conditions, substrate 4 afforded a mixture of the corresponding stereoisomers 11 (25%) and 12 (63%). The observed
The functionalization of the B- ring of the scalarane framework has been achieved for the first time by a radical relay halogenation (RRH) synthetic method. The known scalaranic methyl ester, which was prepared by a procedure with an overall yield higher than those reported in the literature, has been used as the starting substrate. Some theoretical considerations explaining the course of RRH reaction are also presented. (C) 2007 Elsevier Ltd. All rights reserved.
Studies towards the synthesis of cheilanthane sesterterpenoids: superacidic cyclisation of methyl 13Z,17Z- and 13Z,17E-bicyclogeranylfarnesoates
作者:Nicon Ungur、Veaceslav Kulciţki、Margherita Gavagnin、Francesco Castelluccio、Pavel F Vlad、Guido Cimino
DOI:10.1016/s0040-4020(02)01399-6
日期:2002.12
Superacidic low temperature cyclisation of bicyclogeranylfarnesoic acid methyl esters (1 and 2) exhibiting the 13Z-configuration afforded cheilanthane and rearranged cheilanthane terpenoids as main products, along with scalarane compounds. In particular, 14-epi-cheilanthanic ester (6) was obtained together with 18-epi-scalaranic ester (5) by cyclisation of 13Z,17Z-bicyclogeranylfarnesoic acid methyl