BROMINATION OF STEROID 20-KETALS

1959 ◽  
Vol 37 (2) ◽  
pp. 345-350 ◽  
Author(s):  
Arthur A. Amos ◽  
P. Ziegler
Keyword(s):  
Methyl Ester ◽  
Acid Hydrolysis ◽  
Good Yield ◽  
Acid Methyl Ester ◽  
Acid Methyl ◽  
Hydrolysis Of

Bromination of 3α,12α-diacetoxypregnan-20-one ethylene ketal provided in good yield the corresponding 21-monobromo compound. This product, on acid hydrolysis and subsequent acetolysis, gave the known 3α,12α,21-triacetoxypregnan-20-one. Acid hydrolysis of the bromoketal, followed by Faworsky rearrangement, led to 3α,12α-diacetoxy-17α-methyletiocholanic acid methyl ester.

Derivate des Benzo[1.3]dioxols, 431 Über Benzo [1.3] dioxolcarbonsäuren / Derivatives of 1,3-Benzodioxoles, 43 1,3-Benzodioxolecarboxylic Acids

1978 ◽  
Vol 33 (7-8) ◽  
pp. 465-471
Author(s):  
Franz Daliacker ◽  
Volker Mues ◽  
In-O Kim
Keyword(s):  
Carboxylic Acid ◽  
Methyl Ester ◽  
Benzoic Acid ◽  
Myristic Acid ◽  
Good Yield ◽  
Acid Ester ◽  
Acid Methyl Ester ◽  
Acid Methyl ◽  
Derivatives Of

Abstract We describe the possibilities of formation and preparation of the “natural” 1,3-benzodioxolecarboxylic acids 1, 2, 4, 6 b, and 7, already mentioned in literature. Myristic acid (3e) was prepared in good yield from 3-methoxy-4,5-dihydroxy-benzoic acid ester (3c) , which could be easily made from 3-methoxy-2,3-carbonyldioxy-benzoic acid methylester (3b). Myristicic acid methylester (3d) could be subjected to methylation and hydrolysis leading to 3e without any difficulties. 4.6-dimethoxy-1,3-benzodioxole-5-carboxylic acid (5b) was prepared in good yields by oxidation of 4,6-dimethoxy-1,3-benzodioxole-5-aldehyde (5a). 5.7-dimethoxy-1,3-benzodioxole-carboxylic acid (13f), one of the “unnatural” 1,3-benzodioxolecarboxylic acids, derivatives of o-ipiperonylic acid (8), was prepared from 5-amino-7-methoxy-1,3- benzodioxole-4carboxylic acid methyl ester (13b) by diazotisation, elimination of nitrogen, methylation, and hydrolysis. A comparison of our measured pkA-values showed the strongest acidity belonging to 5,6-dimethoxy-1,3-benzodioxole-4-carbocylic acid (11).

4,5-Seco-4,6-cyclosteroids. II. Synthesis of 4,5-Seco-4,6-cyclo-6β-cholestan-5α-ol

1969 ◽  
Vol 22 (3) ◽  
pp. 627
Author(s):  
DJ Collins ◽  
JJ Hobbs ◽  
RJ Rawson
Keyword(s):  
Methyl Ester ◽  
Acid Hydrolysis ◽  
Acid Methyl Ester ◽  
Lithium Aluminium Hydride ◽  
Lithium Aluminium ◽  
Acid Methyl ◽  
Successive Reduction ◽  
Ethylene Acetal

5-oxo-4,5-secocholestan-4-oic acid methyl ester (XIIIb) was converted into the corresponding cyclic ethylene acetal (XIVb) which, upon successive reduction with lithium aluminium hydride and acid hydrolysis, gave 4-hydroxy-4,5-secochol-estan-5-one (XVa), converted into the tosyl ester (XVb). Base-catalysed intra-molecular alkylation of the latter gave mainly A-homo-4a-oxacholest-5-ene (XVII), together with 4,5-seco-4,6-cyclo-6β-cholestan-5-one (IIIc), reduced with lithium aluminium hydride to 4,5-seco--1,6-cyclo-6β-cholestan-5α-ol (IIb). This was identical with material previously prepared by transformation of 4,5-seco-4,6-cyclo-6β-cholestane-3β,5α-diol (IIa), obtained from reductive rearrangement of 6β-bromo-4β,5-epoxy-5,β-cholestan-3β-ol (I). ��� Some other approaches to the synthesis of 4,5-seco-4,6-cyolo-6β- cholestane derivatives are described.

scholarly journals Interference by Methyl Levulinate in Determination of Total Fat in Low-Fat,High-Sugar Products by Gas Chromatographic Fatty Acid Methyl Ester (GC-FAME) Analysis

1999 ◽  
Vol 82 (3) ◽  
pp. 766-769 ◽  
Author(s):  
Fred J Eller
Keyword(s):  
Fatty Acid ◽  
Methyl Ester ◽  
Fatty Acid Methyl Ester ◽  
Acid Hydrolysis ◽  
Acid Methyl Ester ◽  
Low Fat ◽  
High Sugar ◽  
Acid Methyl ◽  
Methyl Levulinate ◽  
Total Fat

Abstract Gas chromatographic fatty acid methyl ester (GC FAME) analyses of some acid-hydrolyzed foods revealed a large peak that did not correspond to any FAME standards. The unknown peak eluted just after the C12 FAME. If the fatty acid response factor and the conversion factor for the nearest calibrated peak (C12 FAME) were used to determine the total fat, the resulting total fat determination was much higher than expected. This peak was present only in acid-hydrolyzed samples and was absent in extracts obtained with supercritical CO2 or solvents without acid hydrolysis. The compound was isolated, analyzed by mass spectrometry and nuclear magnetic resonance spectroscopy, and proved by synthesis to be methyl-4-oxopentanoate (methyl levulinate). Its source was determined to be sugar in the product formula. Levulinic acid is produced by acid hydrolysis of sugar and is transesterified by BF3 in methanolto methyl levulinate. Although methyl levulinate may appear in the GC analyses of any acid-hydrolyzed products containing sugar, if the ratio of fat to sugar is high, the impact of methyl levulinate on fat determination would be small. Onthe other hand, the presence of methyl levulinate in analyses of low-fat, high-sugar prod ucts is potentially problematic if not recognized, al though GC analysis can account for the presence of this compound.

Separation and characterization of 61- and 57-kDa lipases from Geotrichum candidum ATCC 66592

1992 ◽  
Vol 38 (1) ◽  
pp. 75-80 ◽  
Author(s):  
Tomas Jacobsen ◽  
Otto M. Poulsen
Keyword(s):  
Oleic Acid ◽  
Methyl Ester ◽  
Palmitic Acid ◽  
Initial Velocity ◽  
Acid Methyl Ester ◽  
Geotrichum Candidum ◽  
Acid Methyl ◽  
Oleic Acid Methyl Ester ◽  
Palmitic Acid Methyl Ester ◽  
Hydrolysis Of

Two lipolytic proteins (61 and 57 kDa) present in a Sephadex G-100 fraction of extracellular lipase from Geotrichum candidum ATCC 66592 were separated using high-performance liquid chromatography. Crossed electrofocusing immunoelectrophoresis was used to demonstrate that the 61-kDa lipase fraction contained two forms of lipase with pI 4.5 and 4.7. However, when deglycosylated with endoglycosidase H, the two forms gained an identical pI, 4.6. The 57-kDa lipase fraction contained one form of lipase with pI close to 4.5. Although the 61- and 57-kDa lipases were immunologically identical, the substrate specificity differed. Thus, the 61-kDa lipase hydrolysed palmitic acid methyl ester at an initial velocity of hydrolysis that was 60% of the initial velocity of hydrolysis of oleic acid methyl ester, whereas the 57-kDa lipase hydrolysed palmitic acid methyl ester at an initial velocity of hydrolysis that was only7% of the initial velocity of hydrolysis of oleic acid methyl ester. Key words: Geotrichum candidum, lipases, multiple forms, deglycosylation, substrate specificity.

A synthesis of (−)-deoxypodocarpic acid methyl ester via an enzymatic enantioselective hydrolysis of the key intermidiate enol ester

Tetrahedron ◽  
1989 ◽  
Vol 45 (19) ◽  
pp. 6135-6144 ◽  
Author(s):  
Takeshi Sugai ◽  
Hideaki Kakeya ◽  
Hiromichi Ohta ◽  
Mitsuo Morooka ◽  
Shigeru Ohba
Keyword(s):  
Methyl Ester ◽  
Acid Methyl Ester ◽  
Enantioselective Hydrolysis ◽  
Acid Methyl ◽  
Hydrolysis Of ◽  
Enol Ester
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