Taxodione

Chlorinated taxodione 8 was also found along with taxodione 1 from the stem of Rosemarinus officinalis, although its biological activity is yet to be studied (Scheme 8.2).21 Maytenoquinone 9, a structural isomer of taxodione 1, has been isolated from the roots of several medicinal plants such as Maytenus dispermus,22 Salvia melissodora,23 and Harpagophytum procumbems (devil s claw)24 used in folklore medicine. 

SCHEME 8.9 Improved synthesis of taxodione 1 by Motsumoto and coworkers. 

SCHEME 8.10 Engler s synthesis of taxodione 1 via Diels-Alder cycloaddition. 

Besides taxodione and taxodone, these synthetic approaches have been conveniently modified to synthesize other related derivatives such as ferruginols, sugiols, and royleanones.51-52,56-57,60-62 In addition, the enantiomeric-selective synthesis of (+ )-taxodione 1 has been reported using (—)-abietic acid as the starting material63 or with a chiral ligand in the polyene cyclization process.64... 

In addition to the QM structure of the natural terpene QMs, the reactive oxygen species (ROS) may also play a significant role in the observed biological activities. In the synthesis of taxodione and taxodone, QMs were formed from the catechol precursors through the spontaneous oxidation in the presence of silica gel.7, 8,49-51... 

Kupchan, S. M. Karim, A. Marcks, C. Taxodione and taxodone, two novel diterpenoid quinone methide tumor inhibitors from Toxodiumdistichum.J. Am. Chem. Soc. 1968,90, 5923-5924. 

Mori, K. Matsui, M. Diterpenoid total synthesis. XIII. Taxodione, a quinone methide tumor inhibitor. Tetrahedron 1970, 26, 3467-3473. 

Johnson, W. S. Shenvi, A. B. Boots, S. G. An approach to taxodione involving biomimetic polyene cyclization methodology. Tetrahedron 1982, 38, 1397-1404. 

Haslinger, E. Michl, G. Synthesis of (+ )-taxodione from (—)-abietic acid. Tetrahedron Lett. 1988, 29, 5751-5754. 

Kupchan SM, Karim A, Marcks G, Tumor inhibitors. XLVlll. Taxodione and taxodone, two novel diterpenoid quinine methide tumor inhibitors from Tax-odium distichum,] Organic Chemistry 34 3912—3918, 1969. 

A convenient synthesis of ( )-taxodione, ( )-ferruginol, and ( )-sugiol involved the addition of a substituted benzyl chloride moiety to the aldehyde group of cyclocitral and subsequent oxidation. Cyclization of the product (174) afforded the tricyclic system (175) which was then elaborated further. This... 

ABSTRACT This article reviews the literature published dealing with the synthesis of some bioactive diterpenes. It describes the biological activity and synthesis of only four diterpenes pisiferic acid, camosic acid, triptolide and miltirone. This review excludes the discussions of Taxodione, a bioactive diterpene, because it has already been reviewed [85], The utility of several reagents in the total synthesis of terpenoid compounds has been documented. It can be observed that several routes have been developed for the synthesis of a single diterpene. 

In view of the biological activity of taxodione, some attention has been directed at the introduction of a C-6 carbonyl group. The nor-abietatetraene (56) was converted52 into a cis-glycol which on reaction with formic acid gave the C-6 ketone. As an alternative sequence, hydroboronation and oxidation also gave a C-6 ketone. The photosensitized oxidation of 6,7-dehydro-aromatic diterpenoids [e.g. (57)] has also been studied53 with this objective. However, the products were unsaturated ketones [e.g. (58)]. 

Abietane diterpenes (C61C61C6 with varying degrees of unsaturation) include the 5-LOX inhibitor abietane, the GABA(A) receptor antagonist taxodione and the bitter tastant carnosol. 

Taxodione laxodmm distichum (Taxodiaceae) GABAA-R chloride current... 

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