Diols periodate

Evidence for the formation of diol-periodate esters Diol-periodate esters are recognized as intermediates in the oxidation of 1,2-... 

The formation of diol-periodate esters is supported by physical evidence. The addition of ethane-1,2-diol to periodate solutions causes an initial rapid change in the uv absorption spectrum, followed by a slower change as the oxidation proceeds and lOJ is formed. Similar results are observed for other 1,2-diols except for highly substituted diols such as pinacol (Buist et al ). Buist and Bunton have shown that the cyclic periodate esters formed in alkaline solution from 1,2-diols and periodate can be detected by nmr. The initial fall in pH which occurs in the oxidations of ethane-1,2-diol and lightly substituted diols is also attributed to ester formation (Malaprade, Buist and Bunton ). Cyclic triesters, similar to the cyclic diesters formed from 1,2-diols, are formed from cyclic compounds containing the cis-l,2,3-triol system (Barker and Shaw , Dijkstra and from 1,2-0-isopropylidene-a-D-glucofuranose. In the latter case the presence of the triester has been demonstrated by nmr (Berlin and van Rudloff ). Monoesters of periodic acid have not been detected in any system, but they are postulated as intermediates in the formation of cyclic diesters from 1,2-diols (section 1.3.5). 

Taylor pointed out that the kinetics observed for the oxidation of ethanediol are equally consistent with a mechanism involving the direct formation of the products, and an inactive diol-periodate ester, C, in equilibrium with the reactants, viz. 

Angyal and Young report second-order kinetics for the oxidation of the camphane-2,3-diols. The cis- isomers are oxidised much more rapidly than the trans- isomers, and a temperature of 80 °C had to be used for kinetic measurements on the latter. It seems likely that the rigidity of the camphane skeleton prevents the formation of a cyclic diol-periodate ester from the trans- isomers. Possibly the reaction at 80° is completely different in nature from the normal oxidation of 1,2-diols by periodate. The same workers report that cholestane-3j8,6j8,7a-triol, in which the and 7a hydroxyl groups are axial-axial, is inert towards periodate. 

Vicinal diol Periodic acid Aldehyde or ketone Aldehyde or ketone Iodic acid Water... 

The pinacol hydrate may be used (i) for conversion to pina-colone (see below), and (ii) to illustrate the oxidation of 1,2-diols to aldehydes or ketones by periodic acid (p. 145),... 

In a 500 ml. three-necked flask, equipped with a mechanical stirrer, thermometer and dropping funnel, place 300 ml. of 88-90 per cent, formic acid and add 70 ml. of 30 per cent, hydrogen peroxide. Then introduce slowly 41 g. (51 ml.) of freshly distilled cyclohexene (Section 111,12) over a period of 20-30 minutes maintain the temperature of the reaction mixture between 40° and 45° by cooling with an ice bath and controlling the rate of addition. Keep the reaction mixture at 40° for 1 hour after all the cyclohexene has been added and then allow to stand overnight at room temperature. Remove most of the formic acid and water by distillation from a water bath under reduced pressure. Add an ice-cold solution of 40 g. of sodium hydroxide in 75 ml. of water in small portions to the residual mixture of the diol and its formate take care that the tempera... 

To a mixture of 0.3 mol of the diol (see 111, Exp. 60) and 5 ml of pyridine were added with swirling and cooling in a bath of -30°C 85 g of precooled (-30°C) thionyl chloride. The addition was carried out in 10-g portions over a period of 20 min. The cooling bath was then removed and the temperature of the mixture was allowed to rise to 25 or 30°C in 4 h (occasional cooling may be necessary). Some boiling stones were then added and the mixture was warmed at 40 c for 45 min in a water-pump vacuum. Subsequently, the mixture was vigorously shaken with 200 ml of ice water and 20 ml of pyridine. Three extractions with diethyl ether were carried out. The extracts were successively washed with 3 N HCl and water and... 

A reaction characteristic of vicinal diols is their oxidative cleavage on treatment with periodic acid (HIO4) The carbon-carbon bond of the vicinal diol unit is broken and two carbonyl groups result Periodic acid is reduced to iodic acid (HIO3)... 

Cyclic diols give dicarbonyl compounds The reactions are faster when the hydroxyl groups are cis than when they are trans but both stereoisomers are oxidized by periodic acid... 

Periodic acid cleavage of vicinal diols is often used for analytical purposes as an aid m structure determination By identifying the carbonyl compounds produced the con stitution of the starting diol may be deduced This technique finds its widest application with carbohydrates and will be discussed more fully in Chapter 25... 

Section 15 12 Periodic acid cleaves vicinal diols two aldehydes two ketones or an aldehyde and a ketone are formed... 

A diol (CgHig02) does not react with periodic acid Its H NMR spectrum contains three singlets at 8 1 2 (12 protons) 1 6 (4 protons) and 2 0 (2 protons) What is the structure of this dioH... 

Periodic acid oxidation (Section 15 12) finds extensive use as an analytical method m carbohydrate chemistry Structural information is obtained by measuring the number of equivalents of periodic acid that react with a given compound and by identifying the reaction products A vicinal diol consumes one equivalent of penodate and is cleaved to two carbonyl compounds... 

Vicinal diol and a hydroxy carbonyl functions in carbohydrates are cleaved by periodic acid Used analytically as a tool for structure determination... 

A second approach for the synthesis of 6-formylpterin (23) involves the condensation of triamin opyrimidinone (10) with 5-deoxy-L-arabinose (26). The key diol is obtained in four steps starting from compound (10). Cleavage of the diol side chain is achieved either with periodate (39) or with lead(TV) (40) to furnish 6-formylpterin (23) in 45% overall yield. 

A suspension of lithium aluminum deuteride (1.6 g) in dry tetrahydrofuran (60 ml) is added dropwise to a stirred and cooled (with ice-salt bath) solution of 5a-androst-l4-ene-3j3,17j3-diol (179, 1.6 g) and boron trifluoride-etherate (13.3 g) in dry tetrahydrofuran (60 ml). The addition is carried out in a dry nitrogen atmosphere, over a period of 30 min. After an additional 30 min of cooling the stirring is continued at room temperature for 2 hr. The cooling is resumed in a dry ice-acetone bath and the excess deuteriodiborane is destroyed by the cautious addition of propionic acid. The tetrahydrofuran is then evaporated and the residue is dissolved in propionic acid and heated under reflux in a nitrogen atmosphere for 8 hr. After cooling, water is added and the product extracted with ether. The ether... 

Estr-5(10)-ene-3a,17 -diol (10 g, 36.2 mmoles) is added over a period of 1 hr to a refluxing mixture consisting of 60 g (0.92 moles) of zinc-copper couple, 350 ml of dry ether and 180 g (54 ml, 0.67 moles) of methylene iodide. After the addition is complete, half of the solvent is removed by distillation and 200 ml dry ether is added. The reaction mixture is then transferred to a sealed stainless steel tube and maintained for 3 hr at 92° before being cooled in an ice bath and poured into 500 ml of saturated aqueous sodium bicarbonate solution. The resultant mixture is extracted with ether and the extracts are dried over anhydrous sodium sulfate and concentrated to yield a solid residue which gives 8.4 g (80%) 5,19-cyclo-5a,10a-androstane-3a,17) -diol mp 161-163° [aJo 40° (CHCI3), on crystallization from acetone. 

Cyanoandrost-5-ene-3jS,17-diol 3-Acetate Acetic acid (385 ml) is added during a 40 min period at 10° to a stirred mixture of 60 g of 3) -liydroxy-androst-5-en-17-one acetate and 360 g of potassium cyanide in 2 liters of alcohol. The mixture is stirred for 1 hr at 10° and then for 2 hr at room temperature. After dilution with water the precipitated product is collected by filtration, washed with 3 liters of 2 % acetic acid and dried at room temperature. The yield of epimeric cyanohydrins (mp 124° dec [ajj, —93°) is essentially quantitative. 

Periodic acid, 147, 151 Perlauric acid, 6 Persulfuric acid, 152 7-Phenylcholest-5-ene-3, 7 -diol, 60 Phenyliodosoacetate, 184, 221 Phenyllithium, 84... 

Since 1,5-enediones are usually obtained via pyrylium salts, syntheses of the type found in Section B, 2, a have a rather theroetical interest, save for a few special syntheses. There exist several direct syntheses of l,5-enediones, e.g., from j8-chlorovinyl ketones and j8-diketones or j8-keto esters special pathways to 1,5-enediones have also been described, namely, oxidation with lead tetraacetate or with periodic acid of cyclopentene-l,2-diols. ... 

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