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Steroid-21-oates methyl

Like in Chapt. 7, we begin the discussion with acetates, since acetic acid is the simplest nontoxic acyl group, formic acid being less innocuous. An informative study was carried out to compare the kinetics of hydrolysis of two types of corticosteroid esters, namely methyl steroid-21-oates (which are active per se) and acetyl steroid-21-ols (which are prodrugs), as exemplified by methyl prednisolonate (8.69) and prednisolone-21-acetate (8.70), respectively [89]. In the presence of rat liver microsomes, the rate of hydrolytic inactivation of methyl steroid-21-oates was much slower than the rate of hydrolytic activation of acetyl steroid-21-ols. Thus, while the Km values were ca. 0.1 -0.3 mM for all substrates, the acetic acid ester prodrugs and the methyl ester drugs had Vmax values of ca. 20 and 0.15 nmol min-1 mg-1, respectively. It can be postulated that the observed rates of hydrolysis were determined by the acyl moiety, in other words by the liberation of the carboxylic acid from the acyl-enzyme intermediate (see Chapt. 3). [Pg.472]

D. Kumari, H. J. Lee, Hydrolysis of Methyl Steroid-21-oates and Acetyl Steroid-21-ols by Rat Liver Microsomes , Drug Metab. Dispos. 1985, 13, 627-629. [Pg.541]

Isomerization of the diterpeue A B ring juncture. The steroidal type A/B ring juncture of diterpenes can be isomerized to the antipodal one by treatment with a 10% palladium-charcoal catalyst in refluxing triglyme. Thus methyl 5a,10 -podocarpa-8,1 l,13-triene-15-oale (1) can be isomerized in 83% yield to methyl 5j, IOa-podocarpa-8,ll,13-triene-l3-oate (2). The reaction was used in a synthesis of (- J-podocarpic acid from (+)-dehydroabietic acid. [Pg.368]

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... [Pg.138]

Maitra. U. Bag. B.G. Rao. P. Powell. D. Bile acids in asymmetric synthesis. 5. Asymmetric synthesis of steroidal Troger s base analogs. X-ray molecular structure of methyl 3a, 12a- 6H, 12H-5.1 I -methanodibenzo[b,f][l,5]diazo-cine-2,8-bisacetoxy -5P-cholan-24-oate. J. Chem. Soc., Perkin Trans. 1 1995, 2049-2507. [Pg.1524]

Linker, M. and Kreiser, W. (2002) Synthesis of (20R)- and (20S)-epimers of methyl 3-oxochola-l,4, 22-trien-24-oate, a steroid from the octocoral Dendronephthya sp. Hdv. Chim. Acta, 85,1096-1101. [Pg.1417]


See other pages where Steroid-21-oates methyl is mentioned: [Pg.139]    [Pg.763]    [Pg.1107]   
See also in sourсe #XX -- [ Pg.455 ]




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