Determination des configurations par “dedoublement partiel”—III

Horeau, A.; Kagan, Henri B.

doi:10.1016/s0040-4020(01)90823-3

Cited by 215 publications

(45 citation statements)

References 15 publications

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“…In experiments in which 30 umol of steroid, or more, were allowed to react with 2 equivalents of anhydride, the mean optical yields amounted to 42 i 0.3% for VI and 39 0.3% for VII. These values are in substant al agreement with those originally reported (4). When the quantities of steroids were further reduced, a larger excess of anhydride (e.g.…”

supporting

confidence: 91%

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Absolute Configuration of Cecropia Juvenile Hormone

Meyer¹,

Hanzmann²,

Murphy

1971

Proc. Natl. Acad. Sci. U.S.A.

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The absolute configuration of the predominant Cecropia hormone, methyl 12,14-dihomojuvenate, has been determined to be methyl (E,E)-(lORllS)-(+ )-10,11-epoxy-7-ethyl -3,11-dimethyl-2,6-tridecadienoate (I). The less abundant hormone, methyl 12-homojuvenate, can be presumed by analogy to have the corresponding 3,7,11-trimethyldienoate structure (II). The assignment has been established with microamounts of substance by applying Horeau's method to the glycol derivative (III) of the hormone.The course of the perchloric acid-catalyzed epoxide ring opening of I was checked by conducting the conversion in 180-labeled water. It has been ascertained that the configuration at the secondary hydroxyl group of the resulting III remained unchanged. On the other hand, the hydration proceeded with a surprisingly high rate of cis opening.The relative configurations of the two Cecropia juvenile hormones (I, II) have been known for some time (1, 2). The two double bonds in the molecules have the trans or E configuration, whereas the principal carbon chain is cis oriented at the oxirane. This implies R configuration on one of the carbon atoms of the epoxide and S configuration on the other. Recently we reported optical rotatory dispersion data for a mixture of the two natural hormones, and thereby demonstrated [M] yield §

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supporting

confidence: 91%

“…The material was dextrorotatory, implying (see ref. 4) R configuration at the chiral center C-10 of III. The optical yield of the 2.5-pmol experiment amounted to 11%.…”

mentioning

confidence: 99%

Absolute Configuration of Cecropia Juvenile Hormone

Meyer¹,

Hanzmann²,

Murphy

1971

Proc. Natl. Acad. Sci. U.S.A.

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“…In agreement with this view, treatment of either lycocernuine (XII) or dihydrodeoxylycocernuine with a-phenylbutyric anhydride in pyridine (12) leads to an excess of (+)-a-phenylbutyric acid, indicating that the carbinol carbon has the R-configuration Mercuric Acetate Oxidation of Cernuine Cernuine (38 mg) was dissolved in 5% acetic acid (8 ml), and mercuric acetate (0.18 g) was added. The resulting solution was heated in an atmosphere of nitrogen on the steam bath for 42 h and then cooled, and the precipitated mercurous acetate was filtered off.…”

Section: C-~-r R'mentioning

confidence: 64%

The alkaloids of Lycopodium cernuum L. II. The stereochemistry of cernuine and lycocernuine

Ayer¹,

Jenkins²,

Piers³

et al. 1967

Can. J. Chem.

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The relative stereochemistries of cernuine (I) and lycocernuine (11) have been derived by a combination of chemical and physical methods. Evidence is presented which indicates that I and I1 also represent the absolute stereochemistry of these alkaloids. The stereochemistry of allocernuine is discussed, and the isomerization of allocernuine into epiallocernuine is described.Canadian Journal of Chemistry. Volume 45, 445 (1967) In part I of this series (1) we proposed structures I and I1 (stereochemistry unspecified) for the L. cernuum alkaloids cernuine and lycocernuine, respectively, and demonstrated, by transformation of lycocernuine into cernuine, that the two have the same skeletal stereochemistry. I t is the purpose of this paper to show that the relative and absolute stereochemistry of these alkaloids is that represented by I and 11. _ T h e starting point for the determination of the relative stereochemistry of the alkaloids was the assignment of the configuration of the hydroxyl group in lycocernuine. The proton geminal to the acetoxyl group in 0-acetyllycocernuine 'Fellow of the Alfred P. Sloan Foundation. Fellow, 1965Fellow, -1966 (111) gives rise to a signal a t T 5.12 in the nuclear magnetic resonance (n.m.r.) spectrum of 111. This signal appears as a multiplet, with a half-height width of 5 c.p.s. Simultaneous irradiation a t T 6.81 (presumably the C-13 proton) causes the signal a t T 5.12 to collapse to a triplet (splitting ca. 2.5 c.p.s.), whereas irradiation a t T 8.12 (presumably the C-11 methylene) causes it to collapse to a doublet (splitting 2.1 c.p.s.). This result demonstrates the equatorial nature of the proton geminal to the hydroxyl group (2, 3), and thus the axial nature of the hydroxyl group. The ease of elimination of the C-12 substituent (1) is in accord with this assignment. Wniversity of AlbertaThe hydroxyl group in lycocernuine gives rise to a concentration-independent band a t 3 620 cm-l in the infrared (CC14 solution), indicating that it is not involved in For personal use only.

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“…The mass spectrum of 6 exhibited the parent ion peak at m/e 226. These data indicated the molecular formula C Ig H 22 0 g for the monomethyl ester (6), and consequently the molecular formula CI2H200g for cucurbic acid (3).…”

mentioning

confidence: 83%

“…Its IR spectrum (CHCla) indicated the presence of a hydroxyl (3600 cm-1 ), a carboxyl (2800",,2400 and l712cm-1 ) and a carbon-carbon double bond (1655 cm-1 ). Methylation of cucurbic acid (3) with ethereal diazomethane gave a monomethyl ester (6), whose PMR spectrum (CDCla) showed the signals assignable to a primary methyl (0 0.94, 3H, t., J=7 Hz), methylenes and methines (0 1.2""2.8, 12H, undissolved m.), a carbomethoxyl (0 3.65, 3H, s.), a hydroxy-methine proton (0 3.98, IH, m.) and two olefinic protons (0 5.40, 2H, m.). The mass spectrum of 6 exhibited the parent ion peak at m/e 226.…”

mentioning

confidence: 99%