Periodic acid degradation

Periodic Acid Degradation 17a,20 -Dihydroxy-4,4,6,16a-tetramethyl-pregn-5-en-3-one (0.3 g) is dissolved in 30 ml of methanol and treated with an aqueous solution of 0.25 g of periodic acid in 5 ml of water at room temperature for 17 hr. On dilution with water, the resultant crystals are collected by filtration, washed well with water, and dried to give 0.26 g mp 158-160°. Recrystallization from hexane-acetone gives 0.24 g (90%) of 4,4,6,16a-tetramethylandrost-5-ene-3,17-dione mp 160-161° [aj —6° (CHCI3). 

From the oxo reaction of 3,4,6-tri-O-acetyl-D-galactal (36) (after deacetylation of the mixture of products), there was obtained, in almost quantitative yield, 2,6-anhydro-3-deoxy-D-golacto-heptitol (37) and 2,6-anhydro-3-deoxy-D-foio-heptitol (38). - Structural investigations of these anhydrodeoxyalditols paralleled those on the alditols obtained from 3,4,6-tri-O-acetyl-D-glucal. The absolute structures of compounds (37) and (38) were unequivocally established by correlation, as shown, with 2,6-anhydro-3-deoxy-D-gZuco-heptitol (27). Prior structural work" on compound (37), with the aid of periodic acid degradations only, had led to an incorrect, tentative assignment of structure. 

Several acetylated glycals have been subjected to this reaction, and the main products obtained after deacetylation are (despite an initial report to the contrary ) the 2,6-anhydro-3-deoxyalditols. Thus, for example, 1,5-anhydro-4-deoxy-D-lj/xo-hexitol (42) (a 2,6-anhydro-3-deoxyhexitol), and the it-ribo isomer, were isolated in high combined yield, in the ratio 1 0.7, from di-O-acetyl-D-arabinal, after hydroformylation followed by deacetylation and reduction of the formyl compounds (which are produced together with the anhydrodeoxyalditols). Structural analyses of the products were carried out with the aid of periodic acid degradations, nuclear magnetic resonance spectroscopy, and x-ray crystallographic analysis. ... 

In Summary Oxidative cleavage with periodic acid degrades the sugar backbone to formic acid, formaldehyde, and CO2. The ratio of these products depends on the structure of the sugar. 

Hofmann degradation of the nonnatural protoberberine 454 afforded the 10-membered ring base 455 (65%) in addition to the styrene-type compound (13%) (Scheme 92). Dihydroxylation of the former with N-bromosuccinimide in the presence of a large excess of hydrochloric acid and subsequent oxidation of the product diol 456 with periodic acid afforded the dialdehyde 457. On irradiation in tert-butyl alcohol 457 provided ( )-cis-alpinigenine (445) along with ( )-alpinigenine (441) as a result of endo and exo intramolecular cycloaddition, respectively, of the intermediate photodienol (221,222). 

By contrast, acetyl CoA does not have anaplerotic effects in animal metabolism. Its carbon skeleton is completely oxidized to CO2 and is therefore no longer available for biosynthesis. Since fatty acid degradation only supplies acetyl CoA, animals are unable to convert fatty acids into glucose. During periods of hunger, it is therefore not the fat reserves that are initially drawn on, but proteins. In contrast to fatty acids, the amino acids released are able to maintain the blood glucose level (see p. 308). 

No oxidation products of sucrose other than those produced by degradation have been described. Oxidation of sucrose with periodic acid has been carried out, but neither the method nor the products need to be considered for the present purpose. 

Oxidative Degradation of Poly(vinyl Alcohol) with Periodic Acid... 

A fuel cell utilizing UDMH as fuel and N02 as oxidant is reported. Operated intermittently over a 3-month period with degradation, it consistently produced a power density of 40mw/ cm2 (40w/ft2). The cell consists of a sandwich of Zr acid phosphate in a polyvinylidene fluoride (PVF) binder and diffuse-catalyst layers of Pt black, Zr acid phosphate and PVF. Pt screens are used as current collectors] 3) G.R. Eske-lund et al, Chemical-Mechanical Mine , PATR 3724 (1968) [A mine feasibility study is reported in which the hypergolic system UDMH—... 

Increased amino acid degradation In the absorptive period, more... 

Their main results may be summarized as follows. The periodic acid oxidation of polyols afforded a method for quantitative determination of these compounds, and it was demonstrated that the first reaction products are carbonyl compounds, themselves in turn degraded from their reducing end. After complete oxidation, it is possible to make an estimate of the consumption of oxidant, as well as of the formic acid and formaldehyde that are produced. The monosaccharides are attacked preferentially at the neigh-... 

Degradation of the Side Chain of A4-Pregnene-ll, 17,20,21-tetrol-3-one (VIII) by Periodic Acid Oxidation.68 Small-Scale Oxidation. To a solution of 25 mg. of A4-pregHene-ll,17,20,21-tetrol-3-one in 1.5 cc. of methanol is added a solution of 40 mg. of periodic add in 0.3 cc. of water. After twenty hours the solution is diluted with water and freed from methanol in vacuum. The residue is extracted with ethyl acetate and ether. The extract is washed with water and sodium carbonate solution, and then dried over anhydrous sodium sulfate. The crystalline neutral product, obtained by evaporation of the solvent, is recrystallized from ether, then sublimed at 160° and 0.01 mm., and finally recrystallized from a mixture of ether and pentane. The yield of hygroscopic, fine needles of A4-androstene-ll-ol-3,17-dione (IX) melting at 189-191° (cor.) is 12 mg., or 60%. 

Potassium periodate, KIO4, when used in dilute sulfuric acid, acts like periodic acid in degrading a-hydroxy acids to aldehydes [775]. 

In saccharides, cleavage by periodic acid or sodium periodate occurs between any carbons possessing/ree hydroxy lie groups. Thus glucosazone treated with periodic acid in aqueous ethanol at room temperature is degraded to the l,2-bis(phenylhydrazone) of mesoxalaldehyde (propanone-dial) in 85% yield [759]. 

Benzal-D-sorbitol is degraded by periodic acid in aqueous dioxane at 35-45 °C to 2,4-benzal-L-xylose [756] (equation 301). 

A special category of ethers are trimethylsilyl ethers. Trimethylsilyl ethers of primary alcohols, on treatment with Jones reagent, give acids [590]. On treatment with A-bromosuccinimide under irradiation, trimethylsilyl ethers yield esters [744]. Secondary alkyl trimethylsilyl ethers are converted into ketones by oxidation with both reagents [590, 744, 981]. Oxidation with Jones reagent is regiospecific the 2-ferf-butyldimethylsilyl 11-Krf-butyldiphenylsilyl ether of 2,11-dodecanediol is oxidized only in the sterically less hindered position [590]. Trimethylsilyl ethers of tertiary alcohols are degraded by periodic acid to carboxylic acids with shorter chains [755] (equations 336-339). 

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