Ester-alkaloids

If a molecule contains several asymmetric C atoms, then the diastereomers show diastereotopic shifts. Clionasterol (28a) and sitosterol (28b) for example, are two steroids that differ only in the absolute configuration at one carbon atom, C-24 Differing shifts of C nuclei close to this asymmetric C atom in 28a and b identify the two diastereomers including the absolute configuration of C-24 in both. The absolute configurations of carboxylic acids in pyrrolizidine ester alkaloids are also reflected in diastereotopic H and C shifts which is used in solving problem 54. 

Aluminium oxide Strong Steroids, esters, alkaloids... 

N.A. Valeriana officinalis L. Essential oil, valtrate, valepotriates, bomyl esters, alkaloids, isovaltrate.99-100 Sedative for nervous disorders, antispasmodic. 

The sugar alkaloid colchicoside and its synthetic sulfur analog thiocol-chicoside were acylated with esters of trifluoroethanol and with isopro-penylacetate in pyridine in the presence of the enzyme subtilisin from Bacillus subtilis (132). The 13C-NMR spectra of the ester alkaloids, which... 

Three minor ester alkaloids, abresoline (66), demethoxyabresoline (68), and 5-epidemethoxyabresoline (70), have been isolated from Heimia salicifolia by Schwarting et al. (51). 

Two minor ester alkaloids, subcosine-I (69) and subcodine-II (67), have been isolated recently by Fuji et al. (16) from Lagerstroemia subcostata. 

Occurrence of simple quinolizidone alkaloids, ester alkaloids, and lactonic alkaloids in the same Heimia salicifolia plant species provides further evidence in support of current biogenetic hypothesis. 

The rhizome and root of Veratmm album (white hellebore) and the rhizome of Veratrum viride (green hellebore) contain many alkaloids, including hypotensive ester alkaloids and jervine. Veratrum califomicum contains the alkaloids cyclopamine, cycloposine, and jervine. 

Interest has been expressed by the People s Republic of China in the preparation of cephalotaxine ester alkaloids and analogues, no doubt for the purpose of evaluation of antitumour activity. Thus a number of esters, e.g. (34), (R = Me2CHCH2CH2COCO or PhCOCO), were subjected to Reformatsky reaction with methyl bromoacetate to give, e.g., [34 R = Me2CHCH2CH2C(OH)-(CH2C02Me)C0] (deoxyharringtonine) and [34 R = PhC(0H)(CH2C02Me)C0]. 

Alkaloid synthesis. BUchi and Manning transformed ibogaine (5) into the naturally occurring ester alkaloid voacaagine (9) by the four-step process formulated. Treatment of ibogaine with r-butyl hypochlorite afforded the chloroindolenine (6),... 

The retention times of the non-ester alkaloids and derivatives are listed in Table 4.1 and those of the esters with monocarboxylic acids in Table 4.2. In Table 4.3 the retention times of the macrocyclic diesters are given. 

Phenyl-polydimethyl siloxane OV-3, SE-52 350 Fatty acid methyl esters, alkaloids, drugs, halogenated compounds... 

Aspidofractinine (146), the parent member of this third large subgroup of alkaloids of the aspidospermine group, does not occur widely, and the only recent report of its occurrence is in the stem bark and root bark of Hunteria elliottii Pichon (12). Its Na-methyl (147) and Na-methyl-14,15-didehydro (148) derivatives are new alkaloids, which have been found in the roots of Vinca sardoa (67). The ester alkaloids occur much more widely, and several new sources have been reported for (—)-kopsinine (149), (-)-venalstonine (150), (-)-venalstonidine (151), and several minor alkaloids (152-160) (Table I). Of the six reported isolations of 15a-hydroxykopsinine (154), one (16) does not spedfy the configuration of the hydroxyl group. Since it is described as a known alkaloid, it is presumed to be 15a-hydroxykopsinine, because 15/3-hydroxykopsinine is unknown as a natural product. 

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