Conversion of Neoabietic Acid Into Manool

Wenkert, Ernest; Mahajan, J. R.; Nussim, M.; Schenker, F.

doi:10.1139/v66-386

Cited by 16 publications

(18 citation statements)

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“…(+)-Manool is regularly used as a semisynthetic precursor in the syntheses of both marine and terrestrial natural products, [9][10][11] and our initial target, 5, was also originally synthesized from this compound. 12 Wenkert and co-workers' semisynthesis of 5 incorporated an initial intramolecular aldol condensation of the diketone (12) followed by nucleophilic addition of vinyl magnesium bromide to the resultant 8-hydroxy-13-podocarpanone (13). 12 The apparent si-facial selectivity of the Grignard reaction was corroborated by absorbances consistent with a cis 1,3-diol in the IR spectrum of 5.…”

Section: Resultsmentioning

confidence: 97%

“…Diketone 12 has been previously accessed in 72% and 36% overall yield, respectively, from 11 via oxidation of this compound with either a combination of OsO 4 /HIO 5 at pH 6 or KMnO 4 and subsequent ozonolysis. − We, however, elected to modify our preliminary synthesis of 12 from 11 using an initial high-yielding pyridinium chlorochromate mediated oxidative rearrangement of 11 to give a 2:1 mixture of the E and Z isomers (as determined from NMR analysis) of the α,β-unsaturated aldehyde ( 14 ). Reductive ozonolysis of E / Z - 14 afforded 12 in an overall yield (71%) from 11 comparable with reported yields. − …”

Section: Resultsmentioning

confidence: 99%

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Transformations of Manool. Tri- and Tetracyclic Norditerpenoids with in Vitro Activity against Plasmodium falciparum

et al. 2007

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The known 17-norisopimar-15-ene-8β,13β-diol (5) and five new semisynthetic norditerpenoids, ethyl 17-norabiet-13-( 15)-E-en-8β-ol-16-oate (6), ethyl 17-norabiet-13(15)-Z-en-8β-ol-16-oate ( 7), 17-norpimaran-13R-ethoxy-8,16-olactone (8), 17-norisopimarane-8β,15-diol (9), and 17-norarabiet-13(15)-ene-8β,16-diol (10), were prepared from manool (11). Standard spectroscopic data including X-ray crystal analysis were used to determine the structures of 5-10. All five compounds exhibited in Vitro antiplasmodial activity against the malarial parasite Plasmodium falciparum at varying µg mL -1 concentrations.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Transformations of Manool. Tri- and Tetracyclic Norditerpenoids with in Vitro Activity against Plasmodium falciparum

et al. 2007

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“…We thank Dr. Claudine Pascard for this work which will be published elsewhere [21]. The dextrorotatory tricyclic ether 6 was prepared from [23] and subsequent reduction with LiAlH, led to the diastereoisomeric diols 26 and 27. Surprisingly, the cyclic ether formation from diastereoisomers 26 and 27 was regiospecific.…”

Section: )mentioning

confidence: 99%

Stereochemistry‐Odor Relationships in Enantiomeric Ambergris Fragrances

Ohloff

Vial

Wolf

et al. 1980

Helvetica Chimica Acta

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SummaryTwelve tricyclic ethers of the labdane and ent-labdane series, 5-16, have been synthesized; compounds 6-15 are new. The intramolecular C,,-acetals 1-4 and the tricyclic ethers 5-16 were submitted to an olfactory test which was characterized by an exceptionally high percentage of 'wrong' answers (cJ: Table 1, footnote b). For most compounds specific anosmia, rapidly ensuing fatigue and a high percentage of odor deviation were the most salient features.Pronounced ambergris-like odors were only noted in compounds of the labdane series, and were strongest in ethers 1, 5 and 15, followed by the ethers 9 and 11. In contrast, both labdane derivatives 3 and 7 were practically odorless. Their enantiomers 4 and 8, on the other hand, have relatively strong odors which can only to a limited extent be associated with ambergris-type odors. The pairs of ethers 3/4 and 7f8 are the first recorded examples of optical antipodes in which only one isomer possesses olfactory properties.The human olfactory organ is capable of distinguishing chiral compounds. Odor quality and potency of enantiomeric compounds may show considerable differences. Thus, a distinct differentiation in odor perception could be observed in pairs of enantiomeric monoterpenoid odorants [I-51 and the sesquiterpenoid nootkatone [6]. However, the optical antipodes of low molecular weight 2-alkanols are difficult to distinguish [5], and the enantiomers of camphor cannot be distinguished at all [7]. In 8% of the subjects specific anosmia to (-)-carvone was observed, which dropped to 5% in the case of (+)-camone 181. Owing to its anosmic effect carvone has been considered as the prototype for the minty primary odor [9]. The inability to distinguish olfactorily optical antipodes is termed specific chiral anosmia [2].The intensity of the odor of enantiomeric compounds exhibits as great a variability as does the quality. For example, the odor threshold value of (-)-cawone (0.043 ppm) is about ten times lower than that of its (+)-isomer (0.60 ppm) 181, while the odor threshold value of (+)-nootkatone (0.8 ppm) differs by a factor of about 750 from that of its enantiomer (600 ppm) [6]. However, there are cases in which no quantitative differences exist between enantiomers [8]. An explanation for this irregular olfactory behavior of enantiomeric compounds has not yet been found, i.e. the molecular basis of the chiral odor phenomenon is still unknown.0018-019X/80/7/1932-15$01.00/0 0 1980 Schweizerische Chemische Gesellschaft

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“…signals at 6 0.71, 0.85, 0.97, and 1.26 (CH, groups), and a multiplet at 6 4.9-6.2 (three vinyl hydrogens) (see ref. 5 for an alternative preparation). It was distilled for analysis over a short path at 105", 5 x mm in ammonia-washed Pyrex bulbs.…”

Section: Keto-alcohol8mentioning

confidence: 99%