Approaches to the synthesis of 8-epi-vernolepin from germacrolides

Abstract

As part of our program aimed at the synthesis of bioactive products, the enantiospecific synthesis of 8-epi-vernolepin derivatives, starting from accessible germacrolides, was attempted. Synthesis of (ϩ)-8-O-acetyl-1,2,11β,13-tetrahydro-8-epi-vernolepin (23) from (ϩ)-salonitenolide (6) was performed in nine steps with an acceptable overall yield. On the other hand, the synthesis from (ϩ)-stenophyllolide (5) presented several intrinsic difficulties and was discarded. (ϩ)-Salonitenolide provides one of the most useful raw materials for the synthesis of (ϩ)-vernolepin related compounds preserving its functionalization at C-8.

Preparation, Stereochemistry, and Cytotoxic Activity of the Melampolides from Mikania minima

“…(+)-Salonitenolide ( 3 ) may be isolated from Centaurea calcitrapa . However, for this study, 3 was obtained through side-chain saponification of (+)-cnicin ( 4 ) isolated from C. malacitana , to establish a chemical correlation between 4 and the melampolides from M. minima .…”

Eunicidiol, an Anti-inflammatory Dilophol Diterpene from Eunicea fusca

“…Cope rearrangements of germacrenes and germacrenolides to elemenes and elemenolides, respectively, are known to proceed with high stereospecificity and retention of the configuration at C-10 . While the absolute configuration of fuscol ( 2 ) has been established, the configuration of eunicol ( 3 ) was assumed to be 10 S given its role as a biosynthetic precursor to 2 .…”

Antioxidant Activities of Methanol Extracts of Thirteen Cameroonian Antibacterial Dietary Plants

“…A comparison was made between percentages of DPPH scavenged by test samples and percentages of DPPH scavenged by L-ascorbic acid (using the results of triplicate experiments). [6,7] Leaves, seeds Flavonoids, steroids, terpenoids, cardiac glycosides [6], alkaloid, saponin, tannins, phenols, hydrocyanic acid, and phytic acid [8,9] Antimicrobial [4,6,10] Vernonia hymenolepis (H.F.) Hook (Asteraceae); 42401/ HNC Wounds [11], anticancer [12], fever, stomach ache, diarrhoea, hernia, spleen enlargement [13] Leaves Vernolepin [14,15], vernomenin [15], flavonoids (quercetin, apigenin, and luteolin) [16] Cytotoxic [14], spasmolytic, antiaggregating and deaggregating activities, antitumor activity, antimicrobial [17], insecticide [18], antifilarial [19] Lactuca sativa Linn (Asteraceae); 25624/ SRF.Cam Analgesic, conjunctivitis, tired eyes, insomnia, sedative insomnia [20], anxiety, neurosis, dry coughs, rheumatic pain [21], stimulate digestion, enhance appetite, and relieve inflammation [22] Leaves Phenolic acids, triterpenoids, saponins, phytol [20], carotenoids [23], flavonoids including kaempferol [16], lettucenin-A guaianolide sesquiterpene lactones conjugates, lactucin, deoxylactucin, and lactucopicrin [24] Antimicrobial [4,25], antifungal, antibacterial [26], antitumor [27] antioxidating, analgesic, and antiinflammatory [20], depressant [28] sedative, hypnotic, analgesic, and anticonvulsant [29], hypoglycaemic [30], antioxidant l [31,32], and anxiolytic Lactuca ...…”