514-46-5Relevant academic research and scientific papers
PROCESS FOR THE PREPARATION OF LANOSTA-8-ENE COMPOU
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Page/Page column 4-5, (2010/04/03)
The present invention concerns a process for the preparation of lanosta-8-ene compounds having lanosta-8-ene-7-one or lanosta-8-ene-7-ol compounds as starting material.
Cationic Cyclization of a Substrate Having an Internal Acetylenic Bond. Synthesis of Euphol and Tirucallol
Bartlett, William R.,Johnson, William S.,Plummer, Mark S.,Small, Vernon R.
, p. 2215 - 2224 (2007/10/02)
New methodological studies directed toward the synthesis of tetracyclic triterpenoids bearing the 8,9-olefinic bond involve the acid-catalyzed cyclization of the dienediynol 9 as the key step.Surprisingly the ring closure, giving mainly 10, leads to the euphane rather than the lanostane ring system ( see Scheme I).This discovery has made possible the first synthesis of euphol as well as its C-20 epimer tirucallol.New methodology was developed for the highly stereoselective production of tetrasubstituted olefinic bonds during the synthesis of the pro-C-13,14 olefinic bond of cyclization substrate 9 ( Scheme II).The constitution of ketone 10 was established by conversion into the dione 30 as shown in Scheme III.This racemic material was rigorously identified with the natural enantiomer, prepared by degradation of euphol.Dione l-30, obtained by degradation of the natural product was used for reconstruction of the C-17 side chaine to give euphol (1a) and tirucallol (1c); thus a formal totally synthesic pathway to these products has been established.
Synthesis of Some 3-Oxygenated Tirucalla-7,24- and -8,24-dienes
Boar, Robin B.,Couchman, Lorraine A.,Perkins, M. John
, p. 1052 - 1063 (2007/10/02)
Starting from the readily available elemi acids, reference samples of the title compounds have been synthesised and their constants compared with the available literature data.
Une voie d'acces a la trimethyl-4,4,7a tetrahydro-3aα,4,7,7aα (3H)-benzofurannone-2 a partir des alcoxy-5 trimethyl-4,4,7a hexahydro-3aα,4,5,6,7,7aα (3H)-benzofurannones-2
Rouessac, Annick,Rouessac, Francis,Zamarlik, Henri
, p. 199 - 203 (2007/10/02)
The 5-hydroxy 4,4,7a-trimethyl 3aα, 4,5,6,7,7aα-hexahydro (3H)-benzofuran-2-ones are obtained by cleavage of the corresponding methyl or ethyl ethers with iodotrimethylsilane.The two hydroxylactones 5 and 6 are transformed into sulfonic esters as a step towards the dehydrated lactone 7, without squeletal rearrangement.Solvolysis of the tosylate and the mesylate of 5, a cis-fused ring lactone, proceeds by completely different ways under analogous experimental procedures.Results are explained and compared to the solvolysis of some triterpenes.Experimental procedures for ether cleavage are discussed and the intermediates or by-products of these reactions are identified.
