Studies on Agarofurans Ⅳ. The Synthesis of 4-Substitutioned Agarofurans

Agarowoodoilwasfoundtobebioactiveinpharmacologicalscreeningforthenervoussysteminourinstitute.AgarofuransareonesmicturaltypeoftheimportantconstituentSofagarowoodoil.Q-Agarofuran(lh),oneofthemanyconstitUentsoftheoil,issuspectedofbeinganimportantcontributortothebioactivity.AlthoughseveralsynthesisofQ-agarofuran(fo)havebeendescribed'-',theyarenotsuitableforthesynthesisofitsanalogs.Thebioactivitiespromptedustodevelopanewroutetoa-agarofuran(fo)anditsanalogs.EarliersynthesisofQ-agarofuran(lb),with…     

Studies on Agarofurans VI. The Introduction of Substituents to C-1 and C-2 Positions of Agarofurans

Agarofurans have been found to be active on the nervous system in our institute. Since no member of natural agarofurans has C-1 or C-2 substituents, we decided to synthesize ketone 1 and 2, for the convenience of further modification.Our synthetic design for ketone 1, outlined in Scheme 1, was to employ β-epoxide 3 as starting material. Reaction of epoxide 3 with CH3MgI cooled with ice-bath afforded alcohol 4 in 50% yield and reductive product 5 in 40% yield. The structure of 5 has been de…     

Studies on Agarofurans VIII. Synthesis of the Metabolites of 4-Butyl-a-agarofuran

Agarofurans have been found to be active on the nervous system in our institute. 4-Butyl-a-agarofuran 1 is a promising drug candidate. In order to explore the pharmacokinetics of 1, the metabolism of 1 in vitro was studied with liver microsomes from rats. Five metabolites were isolated and structures were identified as compounds 2-6. But the absolute configuration of 2,4,5 and the position of carbonyl in 3 could not be unambiguously determined. Further determination was limited by the smal…     

Studies on Agarofurans Ⅲ. The Synthesis of 3-Substituted Agarofurans

Agarotlirans were found to be bioactive on nervous system. 3,4-dihydroxy dihydroagarofuran (l)' is only one of this group of natural products, which has substituent on C3 position.We synthesized this compound by the reported nletllod' and tbund it to possess somespecific bioactivity on nervous system. In order to search for more active compounds, wedecided to modify agarofurans on C-3 position beginning with the synthesis of 14-nor-3oxodihydroagarofuran (2).In the initial stage of the synthes…     

Studies on Agarofurans V. Studies on the Reductive Ring-Opening of 3,4-Epoxide of Agarofurans

The nature of reductive ring-opening of epoxide has been widely studied. But epoxides of agarofurans with rigid skeleton have their own specificity. Agarofurans have been found to be active on the nervous system in our institute. Reduction of epoxides may afford different types of agarofurans. This prompted us to investigate the reaction.Epoxides 1, 2, 3 were prepared by oxidation of their corresponding olefins1. Generally, the nature of the reduction of epoxides with LAH depends on the ster…     

怀念李裕林先生

记述了我国著名有机合成化学家、兰州大学资深教授李裕林先生在祖国的大西北近半个世纪的学术生涯中的主要贡献,其中包括三尖杉酯碱类化合物的半合成,以及生物标志化合物、狼毒素、大环二萜类、桉烷类和沉香呋喃类天然产物的全合成研究。     

Studies on Agarofurans IV. The Synthesis of 4-Substitutioned Agarofurans

A new synthetic route for α-agarofuran(1b) is described. Several agarofuran derivatives were synthesized in similar way. Derivative 1d was also synthesized in a novel way, in which the substitution at C-4 was performed quantitatively. An ideal condition for cyclization of diol 7 to agarofuran (1) was found.