1686-64-2Relevant academic research and scientific papers
Synthetic Transformations of Higher Terpenoids. 41. Synthesis and Anti-Inflammatory Activity of 4-(Carboxyalkyl)-18-nor-isopimara-7,15-Dienes
Borisov, S. A.,Gromova, M. A.,Kharitonov, Yu. V.,Rybalova, T. V.,Shul’ts, E. E.,Tolstikova, T. G.
, p. 55 - 64 (2022/02/25)
Synthetic methods were developed for isopimaric acid derivatives, the terminal carboxylic acid of which was separated by two or three methylenes from the tricyclic skeleton. Their anti-inflammatory activity was studied. A Wittig reaction of isopimarinal (obtained from isopimaric acid) with the phosphorus ylide generated from methoxymethyl(triphenyl)phosphonium chloride using butyllithium formed a mixture of (Z)- and (E)-alkenes (54% yield) and 4-[(Z)-pentenyl]-18-nor-isopimara-7,15-diene (17% yield). Hydrolysis of the mixture of enol ethers by p-toluenesulfonic acid in Me2CO produced 4-(2-oxoethyl)-18-nor-isopimara-7,15-diene. Olefination of pimarinal and its homolog by a Horner–Wadsworth–Emmons reaction led to the corresponding ethers of (E)-alkenes (81–85% yield). Reduction of the double bond by Mg in MeOH and hydrolysis of the ethers proceeded smoothly to the corresponding 4-(carboxyalkyl)-18-nor-isopimara-7,15-dienes (74 and 88% yield). The structure of 4-(2-carboxyethyl)-18-nor-isopimara-7,15-diene was established by an X-ray crystal structure analysis. Significant anti-inflammatory activity of the new C4-modified isopimaric acid derivatives was found in in vivo tests.
Partial Synthesis of 9,10-Syn Diterpenes via Tosylhydrazone Reduction: (-)-(9β)-Pimara-7,15-diene and (-)-(9β)-Isopimaradiene
Chu, Min,Coates, Robert M.
, p. 4590 - 4597 (2007/10/02)
(9β)-Pimara-7,15-diene (3), a proposed intermediate in the biosynthesis of the momilactone phytoalexins (1 and 2) from rice, and its C-13 epimer, (9β)-isopimara-7,15-diene (4), were synthesized from methyl pimara- and isopimara-8,15-dien-18-oates (8b and 8a, respectively).Allylic oxidation of 8a and 8b as well as the derived diterpene hydrocarbons 15a and 15b with chromium trioxide-dipyridine complex afforded 8,15-dien-7-ones 9a, 9b, 16a, and 16b (35-54percent).Lithium-ammonia reduction of 9a, 16a, and 16b gave predominantly trans,anti,trans-isopimara- and -pimara-15-en-7-ones 10, 17a, and 17b.In contrast, catecholborane reduction of the tosylhydrazones of 9a and 9b provided methyl (9β)-isopimara- and (9β)-pimara-7,15-dien-20-oates (23a and 23b) having the 9,10-syn stereochemistry.The parent diterpenes, 3 and 4, were obtained by carboxyl-to-methyl conversions.In a collaborative investigation 3 was tentatively identified as one of five diterpene hydrocarbons produced upon incubation of (E,E,E)-geranylgeranyl pyrophosphate with a crude enzyme extract from UV-treated rice plants.
