Communic acids

Cupressaceae Juniper, Cupressus, Tetraclinis articulata (sandarac) Pimaradienic acids (sandaracopimaric acid), communic acid, totarol... 

Agathic acid Agatholic acid Communic acid... 

Amber deriving from the extinct species Pinus succinifera is known as Baltic amber or succinite and consists of dimers of abietic acids and copolymers of communol and communic acid. Amber is less soluble than the other resins, but partially soluble in hot oil, so it has been used as an ingredient in varnish. 

Copals, sometimes referred to as immature amber, originate from Africa, Asia or central American countries and derive from the Araucariaceae and Leguminosae families. Polymerised communic acid and agathic acid are found as the main compounds in these fossil resins. The extreme hardness of copal results from polymers of resin acids such as ozoic acid, an enantiomer of communic acid that can polymerize and thus enable fossilization [86]. They are still commonly used today for varnishing and protecting wood. 

The route could start from the mixture of cis- and /rans-communic acids (or also from other diterpenes, such as isocupresic acid). The isolation of hydroxyacid I as a natural product from Acrostalagmus reinforces the possiblity of the existence of diene II as a key precursor, not only of isoacrostalidic acid and acrostalidic acid, but also of dilactone III. The straightforward chemical conversion of I into III in a recent publication by Barrero et al. [20] supports this hypothesis. 

Recently, Barrero et al. have synthesized 63 from cis- and trans-communic acids (153) [14], natural substances present in the cones of Juniperus communis L. Two of the four rings, and three asymmetric carbons have the same configuration as the final molecules. These syntheses were achieved in 10 steps with overall yields of 7% and involves as key steps (Scheme 13) ... 

The same strategy used by Barrero et al. for synthesis of the fungic metabolite LL-Z1271a (63) was used to synthesize nagilactone F (55). Thus, starting from the mixture of communic acids, lactol 99 is achieved, an immediate precursor of both 55 and epimer 165, which are obtained by treatment with isopropylmagnesium bromide. Thus, the synthesis of nagilactone F (55) is completed, with an overall yield of 10%. (Scheme 15). 

Synthesis of Oidiolactone C Starting from Communic Acids... 

The main drawback of the first method described by Barrero et al. [14] for the synthesis of podolactones, lies in the presence of a mixture of three isomers called communic acids (153), which requires a chromatographic separation over silicagel impregnated with 20% silver nitrate to eliminate mirceo-communic acid to allow use of the 2-component mixture of cis- and trans-isomers as starting material. Furthermore, some steps in this former synthetic strategy, such as the closure of the 6-lactone or the formation of the dienolide system need improvement. 

Studying the content in communic acids of the arcestides of different Juniperus and Cupressus sempervirens (Mediterranean cypress), we found the presence of only rrans-communic acid (180) in the arcestides of cypress. Furthermore, this acid could easily be isolated from the acid fraction on the hexane extract by crystallization of its sodium salt. Starting with rrans-communic acid, two diffrent strategies were developed, the first one using diene 186 as the key intermediate, which is summarized in Scheme 19. 

The second synthetic approach to oidiolactone C (61) is summarized in Scheme 20. This route also commences with the ozonolysis of trans-communic acid 180. Now, when this compound was exposed to ozone in excess, keto aldehyde 187 was obtained in 76% yield. The key step in this approach was the y-lactone closure via chemoselective reduction of the lactone moiety on compound 189 through a SN2 mechanism. Compound 189 could be prepared by saponification of the corresponding methyl ester with sodium propanethiolate. Once the primary alcohol is oxidized, the completion of the synthesis of key lactone 103 only requires the allylic oxidation of the C-17 methyl with concomitant closure of the 8-lactone. This conversion was achieved with Se02 in refluxing acetic acid to give 103 in 51% yield. 

The First Synthesis of the Antifungal Oidiolactone C from rrans-Communic Acid Cytotoxic and Antimicrobial Activity in Podolactone-related Compounds. Barrero, A.F. Arseniyadis, S. Quflez del Moral, J. F. Herrador, M. M. Valdivia, M. Jimenez, D. J. Org. Chem. 2002,67,2501-2508. 

Di83 rrans-Communic acid methyl ester T. siandishu EBV [128]... 

Fig. 5-4. Examples of diterpenes and their derivatives in softwood. 1, Geranyl linalool 2, thunbergene 3, /3-epimanol 4, abienol 5, pinifolic acid 6, elliotinoic acid (communic acid).

Organomercuiial intermediates have aiso been utilized in the biotnimetic conversion of communic acids to the pimarane system, during which the radical involved in the NaBH4-demercuration step was captured by oxygen. Treatment of rrnns-communic acid with Hg(OAc)2 (2 equiv.), followed by reduction, led to (44) and (45) and other products. These results are consistent with the intervention of the radical formed fh)m the dimercurial (46) and, indeed, separate reduction in the presence of oxygen provided the peroxy compound (45) directly (Scheme 36). 

Pinus monticola. Further studies on the oleoresin of the white cypress, Callitris columellaris, show that it contains cis- and trans-communic acids, communic acid, sandaracopimaric acid, and 7-oxo-4-epidehydroabietic acid. Dundathic acid is a polymer of communic acid containing ca. four diterpenoid units. 

Woody higher plants can also exude resins. For example, dammar resin from certain angiosperms (e.g. dipterocarps) contains a polycadinene (Fig. 2.26), based on a A5-cadinene monomer (van Aarssen et al. 1990). Gymnosperm resin polymers are based on labdatriene (diterpenoid) monomers such as communic acid (Fig. 2.26 Mills et al. 1984/5 Hatcher Clifford 1997), and some angiosperm resins also contain these polymers. In contrast to polycadinene formation, polymerization of labdatrienes is thought to occur after exudation. 

Epimandol has been detected in the neutral extracts of Larix europaea and in the bark of the Sitka spruce. Cupressus resins have been examined by g.l.c. and imbricatolic acid (5) identified in all but Cupressus sempervirens. This acid co-occurs with the cis- and trans-communic acids and with sandaracopimaric acid. A -Communic acid has been isolated as its methyl ester from Callitris columellaris. During this work the thermal isomerisation of the conjugated diene of communic acid was noted. The structures and stereochemistry of some... 

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