On the synthesis of 3,4-dihydroxyprolines. II. Synthesis, stereochemistry and reactivity of some 3,4-Epoxy-DL-proline derivatives

1975 ◽  
Vol 28 (11) ◽  
pp. 2479 ◽  
Author(s):  
CB Hudson ◽  
AV Robertson ◽  
WRJ Simpson
Keyword(s):  
Acid Hydrolysis ◽  
Methyl Esters ◽  
High Yield ◽  
Butyl Esters ◽  
Epoxy Acids ◽  
Trifluoroperacetic Acid ◽  
Catalytic Hydrogenolysis ◽  
Direct Separation ◽  
Proline Derivatives ◽  
Hydrolysis Of

N-Protected esters of 3,4-dehydro-DL-proline react with trifluoroperacetic acid to give, in high yield, approximately equal amounts of the corresponding stereoisomeric 3,4-epoxy-DL-proline derivatives, direct separation of which proved difficult. However individual members of the two families were obtained by discovery of selective transformations and fractionations. Relative configurations of the two 3,4-epoxy-N-tosylproline methyl esters were established by borohydride reduction to authentic 4-hydroxy-N-tosylprolinols. Epoxide reduction is regioselective. Extensive p.m.r. analyses then permitted stereochemical assignment of other derivatives. These epoxides are remarkably resistant to catalytic hydrogenolysis, and to hydration in acid or alkali. N-Substituted 3,4-epoxyproline methyl esters undergo ready β-elimination in alkali to yield the corresponding 4-hydroxy-2,3- dehydroproline esters and ultimately the N-substituted pyrrole-2- carboxylic acid or ester. Prolonged aqueous acid hydrolysis of 3,4- epoxy-N-tosylprolines, or of their methyl esters, gives mixtures of 3,4-dihydroxy-N-tosyl-DL-prolines in the 2,3-cis-3,4-trans and 2,3- trans-3,4-trans families. Their stereochemistry was allotted from p.m.r. of the diacetate methyl esters. During acid hydrolysis of 3,4- epoxy-N-tosylproline methyl esters, the ester of the trans stereoisomer hydrolyses selectively, and some epimerization of the cis stereoisomer occurs. Ester hydrolysis is much faster than epoxide hydration. Anhydrous acid cleavage of 3,4-epoxy-N-tosyl-DL-proline t-butyl esters to the epoxy acids is unusually slow.

Enolic Ortho Esters. I. Preparation and Birch Reduction of Some Coumarinoid Ortho Esters

1989 ◽  
Vol 42 (8) ◽  
pp. 1235 ◽  
Author(s):  
DJ Collins ◽  
LM Downes ◽  
AG Jhingran ◽  
SB Rutschmann ◽  
GJ Sharp
Keyword(s):  
Carbon Tetrachloride ◽  
Acid Hydrolysis ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
High Yield ◽  
Ortho Ester ◽  
Birch Reduction ◽  
High Yields ◽  
Ortho Esters ◽  
Hydrolysis Of

Phenolic ortho esters such as 4′,4′-dimethylspiro[2H-1-benzopyran-2,2′-[1,3]dioxolan] (7b) and 4′,4′-dimethyl-3,4-dihydrospiro[2H-1-benzopyran-2,2′-[1,3]dioxolan] (9c) were prepared in low yields by reaction of 2H-1-benzopyran-2-one (5) or 3,4-dihydro-2H-1-benzopyran-2-one (8a) with 2,2-dimethyloxiran in carbon tetrachloride in the presence of boron trifluoride etherate. 3,4-Dihydrospiro[2H-1-benzopyran-2,2′-[1,3] dioxoan ] (9a) and the corresponding 7-methoxy compound (9e) were obtained in high yield by reaction of (8a) or its 7-methoxy analogue (8b) with 1,2-bis(trimethylsily1oxy)ethane (10) in the presence of trimethylsilyl trifluoromethane-sulfonate . Birch reduction of phenolic ortho esters such as (9c) and (9e) afforded the enolic ortho esters 4′,4′-dimethyl-3,4,5,8-tetrahydrospiro[2H-1-benzopyran-2,2′-[1,3] dioxola n] (11a) and 7-methoxy-3,4,5,8-tetrahydrospiro[2H-1-benzopyran-2,2′-[1,3]dioxolan] (llc) in high yields. Birch reduction of 4′,4′,5′,5′-tetramethylspiro[2H-1-benzopyran-2,2′-[1,3]dioxolan] (7c) gave a 1 : 3 mixture of 4′,4′,5′,5′-tetramethyl-3,4-dihydrospiro[2H-1-benzopyran-2,2′-[l,3] dioxolan ] (9d) and the corresponding 3,4,5,8-tetrahydro compound (11b). Acid hydrolysis of the enolic ortho ester (11a) gave 67% of 2-hydroxy-2-methylpropyl 3-(2-oxocyclohex-3-enyl) propanoate (20).

Preparation and synthetic utilization of 3-(adenin-9-yl)-2-hydroxyalkanoic acids and their derivatives

1984 ◽  
Vol 49 (9) ◽  
pp. 2148-2166 ◽  
Author(s):  
Antonín Holý
Keyword(s):  
Alkali Metal ◽  
Acid Hydrolysis ◽  
Malonic Acid ◽  
Sodium Borohydride ◽  
Sodium Periodate ◽  
Methyl Esters ◽  
Metal Cyanides ◽  
Hydroxybutanoic Acid ◽  
Hydrolysis Of ◽  
Synthetic Utilization

Condensation of adenine and its substituted derivatives with 1,1-dialkoxy-2-bromoalkanes afforded substituted 2-(adenin-9-yl)-1,1-dialkoxyalkanes I and IV. Acid hydrolysis of I or IV, followed by reaction with alkali metal cyanides and acid hydrolysis, gave substituted 3-(adenin-9-yl)-2-hydroxyalkanoic acids II, Vand VI. Methyl esters of these compounds (VIII) were converted into 3-(adenin-9-yl)alkane-1,2-diols IX by reduction with sodium borohydride. 3-(Adenin-9-yl)-2-methoxypropanoic acid (XVII) was obtained by oxidation of 9-(3-hydroxy-2-methoxypropyl)adenine (XVI) with sodium periodate; 4-(adenin-9-yl)-2-(S)-hydroxybutanoic acid (XXVII) was synthesized by oxidation of 9-(S)-(2-tetrahydropyranyloxy-4-hydroxybutyl)adenine (XXV), prepared from diethyl L-malate. Acid hydrolysis of XXV afforded 9-(S)-(2,4-dihydroxybutyl)adenine (XXVI). 4-(Adenin-9-yl)-3-hydroxypentanoic acid (XXIX) was obtained by reaction of malonic acid with 2-(adenin-9-yl)-1,1-diethoxypropane (IVa) in water.

Synthesis and Acid Hydrolysis of Monophosphate and Pyrophosphate Esters of Phytanol and Phytol

1973 ◽  
Vol 51 (11) ◽  
pp. 1527-1536 ◽  
Author(s):  
C. N. Joo ◽  
C. E. Park ◽  
J. K. G. Kramer ◽  
M. Kates
Keyword(s):  
Acid Hydrolysis ◽  
Infrared Spectra ◽  
Dipotassium Salt ◽  
Hydrolysis Products ◽  
Elementary Analysis ◽  
Catalytic Hydrogenolysis ◽  
And Behavior ◽  
Hydrolysis Of

Monophytanyl phosphate was synthesized by phosphorylation of phytanol with diphenylphosphoryl monochloride followed by catalytic hydrogenolysis of the phenyl groups; the product was isolated as the dipotassium salt. The phytanyl pyrophosphate was prepared by phosphorylation of phytanol with monophenylphosphoryl dichloride followed by aminolysis and saponification of the resulting phytanylmonophenylphosphoryl monochloride to the phytanyl phosphoramidate. The latter, as the cyclohexylamine salt, was reacted with dioxane diphosphate in the presence of pyridine to give the desired phytanyl pyrophosphate isolated as the tripotassium salt. Alternatively, the phytanyl pyrophosphate was made from phytanyl monophosphate via the phosphomorpholidate. The 2-phytenyl (phytyl) pyrophosphate was synthesized more directly by phosphorylation of phytol with di-(triethylammonium) phosphate in the presence of trichloroacetonitrile in acetonitrile as solvent. The phytyl pyrophosphate and the accompanying phytyl monophosphate were isolated as tri- and diammonium salts, respectively. These mono- and pyrophosphates were characterized by elementary analysis, infrared spectra, and behavior towards acid hydrolysis; the hydrolysis products formed are characteristic of the phytyl or phytanyl phosphate hydrolyzed and may be used for their identification.

scholarly journals Further studies on the glycerol teichoic acid of walls of Staphylococcus lactis I3. Location of the phosphodiester groups and their susceptibility to hydrolysis with alkali

1971 ◽  
Vol 125 (1) ◽  
pp. 353-359 ◽  
Author(s):  
A. R. Archibald ◽  
J. Baddiley ◽  
J. E. Heckels ◽  
S. Heptinstall
Keyword(s):  
Acid Hydrolysis ◽  
Teichoic Acid ◽  
Hydroxyl Group ◽  
High Yield ◽  
Selective Hydrolysis ◽  
Partial Acid Hydrolysis ◽  
Structural Types ◽  
Phosphodiester Group ◽  
Hydrolysis Of ◽  
Alcoholic Hydroxyl

1. The teichoic acid from walls of Staphylococcus lactis I3 is readily degraded in dilute alkali. 2. Degradation proceeds by selective hydrolysis of that phosphodiester group attached to an alcoholic hydroxyl group of the N-acetylglucosamine and gives a repeating unit in high yield. 3. Further studies on a different repeating unit isolated by partial acid hydrolysis have shown that the glycerol diphosphate is attached to the 4-hydroxyl group of the N-acetylglucosamine and not to the 3-hydroxyl group as was proposed earlier. 4. The susceptibility towards hydrolysis by alkali of other structural types of teichoic acid has been examined and found to vary markedly according to their structure.

scholarly journals Xylose Release From Sunflower Stalk by Coupling Autohydrolysis and Enzymatic Post-Hydrolysis

2021 ◽  
Author(s):  
Fatmagül HALICI-DEMİR ◽  
Özlem AKPINAR
Keyword(s):  
Enzyme Activity ◽  
Acid Hydrolysis ◽  
Substrate Concentration ◽  
High Yield ◽  
Dilute Acid ◽  
Dilute Acid Hydrolysis ◽  
Hydrolysis Method ◽  
Optimization Study ◽  
Xylose Production ◽  
Hydrolysis Of

Abstract The purpose of this study was to obtain xylose-based fermentation media from autohydrolysis liquors of sunflower stalk by using commercial xylanase formulation. Xylose is generally produced from xylan by diluted acid hydrolysis that causes the formation of some unwanted compounds during the process. As an alternative to dilute acid hydrolysis method, enzymatic hydrolysis of xylan can provide more specific hydrolysis under moderate conditions and does not cause the formation of undesirable compounds. In this study, xylose production carried out with Trichoderma longibrachiatum xylanase on solubilized xylan form of sunflower stalk, which was hydrothermally pretreated for 1 hour at 160ºC. The effects of substrate concentration and enzyme activity were investigated for the production of xylose. To obtain a high xylose yield and selectivity, the optimization study was conducted by the response surface methodology. The optimum substrate concentration and enzyme activity were found as 60 mg ds/mL CAL and 234 U/mL, respectively. Under the optimum condition, xylose yield and selectivity were found to be 69.5% and 8.2 g/g, respectively. This study showed that xylose could be produce with a high yield without requiring a neutralization process and corrosive chemical reagent apart from water.

DETERMINATION OF MICRO-AMOUNTS OF 5β-PREGNAN-3α-OL-20-ONE IN URINE USING INFRARED-SPECTROMETRY

1962 ◽  
Vol 41 (2) ◽  
pp. 234-246 ◽  
Author(s):  
H. J. van der Molen
Keyword(s):  
Infrared Spectrum ◽  
Quantitative Determination ◽  
Acid Hydrolysis ◽  
Chromatographic Separation ◽  
Pure Form ◽  
Infrared Spectrometry ◽  
Hydrolysis Of

ABSTRACT A procedure for the quantitative determination of 5β-pregnan-3α-ol-20-one in urine is described. After acid hydrolysis of the pregnanolone-conjugates in urine, the free steroids are extracted with toluene. Pregnanolone is isolated in a pure form as its acetate; after chromatographic separation of the free steroids on alumina, the fraction containing pregnanolone is acetylated and rechromatographed on alumina. Quantitative determination of the isolated pregnanolone-acetate is carried out with the aid of the infrared spectrum recorded by a micro KBr-wafermethod. The reliability of the method under various conditions is discussed under the headings, specificity, accuracy, precision and sensitivity. It is possible to determine 30–40 μg pregnanolone in a 24-hours urine portion with a precision of 25%.

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