19907-21-2Relevant academic research and scientific papers
Condensation of Methyl Isopimarate with α,β-Unsaturated Aldehydes on Zeolites
Kuzakov, E. V.,Shmidt, E. N.,Bagryanskaya, I. Yu.,Rybalova, T. V.,Gatilov, Yu. V.,Barkhash, V. A.
, p. 171 - 178 (2007/10/02)
Reactions of methyl isopimarate with α-methylacrolein and acrolein over zeolites occur by two parallel pathways, Δ8(14)- and Δ8(9)-ene condensation, the former pathway being predominant.Under selected conditions, products of Δ8(14)-ene condensation undergo further conversions, namely intramolecular reaction of the aldehyde group with the double bond (similarly to cyclic Prins reaction) and cyclization of the resulting alcohol with perhydrobenzanthrene core to form an oxolane with a new type of skeleton.The direction of condensation of methylpimarate with unsaturated aldehydes is independent of the nature of enophiles and catalysts used.
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.
PART I. EPOXYDES DITERPENIQUES : SYNTHESE ET REACTIVITE D'EPOXYDES DERIVES D'ACIDES RESINIQUES
Papillaud, B.,Tiffon, F.,Taran, M.,Miguel, B. Arreguy-San,Delmond, B.
, p. 1845 - 1858 (2007/10/02)
Epoxidation of methyl esters of resin acids with the pimarane skeleton with p-nitroperbenzoic acid has permitted the isolation of epoxides of the intracyclic double bond.Allylic diterpenic alcohols were obtained by acid-catalysed isomerisation of diterpene epoxides, and the action of Collins reagent on these allylic alcohols has been studied.
