Period acid cleavage

Can you remember what re action of an alkene would give the same products as the periodic acid cleavage shown here" ... 

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... 

Only one site for periodic acid cleavage in methyl a D arabmofuranoside... 

Somewhat milder oxidative conditions lead to loss of but one carbon. Periodic acid cleavage of the side chain in 65, leads to the so-called etio acid (66). Reaction with propionic anhydride leads to acylation of the 17-hydroxyl group (67). Possibilities for neighboring group participation severely limit the methods available for activating the acid for esterification. Best results seemed to have been obtained by use of a mixed anhydride from treatment with diphenyl chloro-... 

Aqueous periodic acid can be used to achieve glycol cleavage, combined with anodic oxidation of the iodate, which is formed, back to periodate [70]. Oxidation of iodate is catalysed at a lead dioxide anode [71] but at the potentials required, aldehydes are oxidised to the corresponding acids. Due to this further reaction, the redox-mediated cleavage of diols to form an aldehyde may be difficult to achieve witli a catalytic amount of periodic acid. Cleavage using a stoichiometric amount of periodic acid, followed by recovery of the iodic acid and then its electochemical oxidation, has been achieved [72]. 

After periodic acid cleavage of the double bond, the aldehyde is oxidi/cd to an acid. What reagents arc best suited to the task a) CrO /HiSO aectone Jones reagent) b) NaC102/NaH >P04/2-methyl-2-butenc c) TPAP d) PCC or e) PDC ... 

P) and concomitant liberation of 1 mol of formaldehyde. This result proves that there is a v/c-glycol present, but it does not prove whether it has an sn-3 or an sn-1 configuration. Obviously, an sn-2 configuration is eliminated by the periodic acid cleavage experiments. 

Diols (glycols), such as those formed by dihydroxylation of alkenes, are cleaved by periodic acid (HI04). The products are the same ketones and aldehydes that would be formed by ozonolysis-reduction of the alkene. Dihydroxylation followed by periodic acid cleavage serves as a useful alternative to ozonolysis, and the periodate cleavage by itself is useful for determining the structures of sugars (Chapter 23). 

Periodic acid cleavage of a glycol probably involves a cyclic periodate intermediate like that shown here. 

Determination of Ring Size Periodic Acid Cleavage of Sugars... 

Periodic Acid Cleavage of Carbohydrates Another method used to determine the size of carbohydrate rings is cleavage by periodic acid. Recall that periodic acid cleaves vicinal diols to give two carbonyl compounds, either ketones or aldehydes, depending on the substitution of the reactant (Section 11-1 IB). 

On the other hand, if glucose were a furanose (five-membered ring), the periodic acid cleavage would give an entirely different set of products. Because glucose actually exists as a pyranose (six-membered ring), these products are not observed. 

Determine the structure of an unknown carbohydrate based on its reactions. Determine its ring size from the methylation and periodic acid cleavage reactions. Problems 23-57, G3, G4, G5, and 66... 

A final demonstration that aconitine possessed the CD ring system as shown was the periodic acid cleavage of oxonine to the secoketoaldehyde... 

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