Derivatives of Dehydroabietic and Podocarpic Acids

Wenkert, Ernest; Beak, Peter; Carney, Richard W. J.; Chamberlin, James W.; Johnston, David B.; Roth, Claris Deane; Tahara, Akira

doi:10.1139/v63-284

Cited by 22 publications

(5 citation statements)

References 16 publications

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“…The physical properties of this substance are consistent with those reported by Wenkert et al (4), who prepared it by a different route. Hydrogenation of 6 yielded methyl 0-methylpodocarpate.…”

supporting

confidence: 90%

Oxidative Degradation of a Podocarpic Acid Derivative

Ho¹

1971

Can. J. Chem.

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The dichromate oxidation of methyl-7-methyl-6,8,11,13-podocarpatetraen-l9-oate, (5), is reported.L'oxydation par le dichromate du mCthyl-7 podocarpatetratne-6,8,11,13 oate-19 (5) de mkthyle est rapportee.Canadian Journal of Chemistry, 49, 2501 (1971) During the study of ring I3 expansion of methyl 0-methylpodocarpate (1) which served as a model in a projected synthesis of aconitine-type diterpene alkaloids (I), we discovered a novel oxidative degradation.It was intended to prepare the exocyclic olefin 2, a useful intermediate for our purpose (2), from the well-known 7-keto derivative 3 of 1.We first attempted the Reformatsky reaction on 3, hoping that further transformations of the product 4 by dehydration, saponification and pyrolysis would yield the desired olefin. Surprisingly, direct acid treatment of the crude product gave only the styrene 5, whose structure followed from spectroscopic data.Wittig olefination (3), when applied to ketone 3, also led to the isomerized product 5. The definite structure of 5 was settled on a firm basis by its preparation by dehydration of the methyl Grignard product of 3.Dichromate oxidation of the styrene 5 gave, unexpectedly, methyl 0-methyl-5,6-dehydro-7-ketopodocarpate (6). The physical properties of this substance are consistent with those reported by Wenkert et al. (4), who prepared it by a different route. Hydrogenation of 6 yielded methyl 0-methylpodocarpate.The mechanistic pathway of the oxidation may be envisaged as outlined in Scheme 1. It is noteworthy that a close analogy of the initial steps may be found in the cleavage of cycloalkenes to dialdehydes by chromyl trichloroacetate (5). ExperimentalMelting points were determined on a Kofler microscope hot-stage and are uncorrected. The i.r. spectra were 'Present address:

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supporting

confidence: 90%

Oxidative Degradation of a Podocarpic Acid Derivative

Ho¹

1971

Can. J. Chem.

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“…The lack of activity of dehydroabietic acid derivatives towards Gram-negative bacteria has already been observed [1], [6]. In a previous work [6], only combined methyl 10a-methyl-7-oxo-13deisopropyldehydroabietate (13) and its 10b-methyl isomer inhibited the growth of Escherichia coli and Klebsiella pneumoniae.…”

Section: Antimicrobial Activity Assaysmentioning

confidence: 83%

“…In order to improve the activity of these compounds additional functions were introduced. Methyl 10a-methyl-7-oxo-13-deiso- Original Paper propyldehydroabietate (13) and the phenol, methyl 12-hydroxy-10a-methyl-13-deisopropyldehydroabietate (16) were obtained from 10, respectively, by a selective photo-oxygenation procedure [5] or by a sequential acetylation, Bayer-Villiger oxidation and hydrolysis methodology [11]. Due to the differences in the experimental procedure used and in the melting point of the compound obtained with that previously reported in the literature, the characterisation of 16 was also done.…”

Section: Synthesis Of the Compoundsmentioning

confidence: 99%

Structural Effects on the Bioactivity of Dehydroabietic Acid Derivatives

Gigante¹,

Silva²,

Marcelo-Curto³

et al. 2002

Planta med

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The synthesis and the evaluation of the antimicrobial activity against a filamentous fungus, yeasts and bacteria of 15 hydrophenanthrene compounds derived from dehydroabietic acid, bearing different functional groups and different stereochemistry of the A/B ring junction are disclosed. The results obtained showed how their activity is dependent of the functionality at C-18, which can be increased by deisopropylation or introduction of other groups into the molecule. While the filamentous fungus tested is sensitive to almost all of the compounds under study, the aldehyde function showed to be of major importance to the inhibition of yeast. Alcohols and aldehyde C-18 derivatives also inhibit the growth of a Gram-positive bacteria, whereas Gram-negative are not sensitive.

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“…9 Moreover, esters of propiolic acids are prone to undergo Michael addition and self-condensation in the presence of amines such as triethylamine that is usually used in Sonogashira reactions. 10 To circumvent these shortcomings, Ipaktschi and Eckert reported a synthesis of aryl propiolates by coupling methyl propiolate with aryl iodides using potassium carbonate as a base. 11 Bearing this in mind, and on the basis of precedent of our previously successful coupling of methyl propiolate with 2-iodobenzaldehyde, we attempted the coupling with 2-halobenzaldehyde 8 in a similar fashion.…”

Section: Paper Synthesismentioning

confidence: 99%