Of podocarpic acid

In 1971, Zalkow and co-workers reported (175) the conversion of podocarpic acid (322) to a key intermediate 323 for the synthesis of the enatiomers of ajaconine (80) and atidine (79). Compound 323 contains the... 

Pinhey utilized the decarboxylative rearrangement of 2 to the nor-alkyl pyridyl sulfide 3, oxidation to the corresponding sulfoxide and thermal elimination sequence in a simple transformation of podocarpic acid 4 into useful synthons 5 (for example, in vitamin D3 synthesis) for steroid CD-ring systems, as shown in Scheme l.8... 

The low-temperature ozonolysis of podocarpa-8,1 l,13-trien-12-ol (59) to form the lactol (60) has been re-examined54 and the importance of slightly acidic reaction conditions has been noted. The conversion of podocarpic acid into 19-hydroxypodocarpa-8(14)-en-13-one has been described.55 The C-12 oxygen function was removed by hydrogenolysis of the 12-toluene-p-sulphonate. Details of the nitration of methyl 7-oxodehydroabietate have appeared.56 The conformational analysis of the ring C diene, levopimaric acid, has been discussed57 in terms of a folded conformation. 

Studies aimed at the synthesis of the tetracyclic steroid skeleton from dehydro-abietic acid have centred, in their initial stages, on transformations of the C-13 isopropyl group. The full paper describing the conversion of methyl 12-acetyl-abieta-8,ll,13-trien-18-oate into methyl 13-hydroxypodocarpa-8,ll,13-trien-18-oate by nitrodeacylation and dealkylation reactions, has appeared. Birch reduction of the methyl ether of the phenol afforded the a/5-unsaturated ketone (56) which is a useful synthetic intermediate. Methods for the conversion of podocarpic acid into the a) -unsaturated ketones (57 R = CO2H and CHjOAc) have been investigated reduction of the ester (58 R = C02Me) with lithium in liquid ammonia, which was accompanied by decarboxylation, gave only a... 

Isomerization of the diterpene A/B ring juncture.6 The steroidal type A/B ring juncture of diterpenes can be isomerized to the antipodal one by treatment with a 10% palladium-charcoal catalyst1 in refluxing triglyme. Thus methyl 5a,10a-podocarpa-8,1 l,13-triene-15-oate (1) can be isomerized in 83% yield to methyl 5/110a-podocarpa-8,ll,13-triene-15-oate (2). The reaction was used in a synthesis of (- )-podocarpic acid from (+)-dehydroabietic acid. 

Syntheses Directed toward Ajaconine and Atidine. The conversion of podocarpic acid (92) into a key intermediate (93) in the synthesis of the enantiomers of the diterpene alkaloids ajaconine (94) and atidine (50) has been reported by 2 1kow and co-workers. The pentacyclic unsaturated keto-lactam (93) was prepared... 

Synthesis and Fungistatic Activity of Podocarpic Acid Derivatives... 

Podocarpic acid (I) was first isolated from the resin of Podocarpus cupressins. an isQ>ortant timber tree which is end nic to Java, and later from Podocarpus dacrydioides ( Kahikatea ) and Dacrydiuro cupressinum ( Rimu ), trees which are found in the timber regions of Hew Zealand (1). Since 1968, more than forty oxygenated metabolites of podocarpic acid have been isolated from various species of Podocarpus (2,3). 

Table I. Comparison of the fungistatic properties of podocarpic acid and its derivatives ...

For example, the cyclomangations of podocarpic acid a-carbonyl compound of diterpenoid easily proceed. Furthermore, the reaction of the above podocarpic acid derivative with an alkyn affords a steroid compound in a high yield by forming an indene ring as shown in eq. (14.31) [79,81]. 

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