Periodate diol cleavage

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... 

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]. 

Intramolecular Dieckmann cyclization of polystyrene-bound pimelates has been used to prepare (l-keto esters (Entry 4, Table 3.41). Oxidative cleavage reactions leading to the formation of aldehydes include the ozonolysis of resin-bound alkenes, the periodate-mediated cleavage of 1,2-diols, and the oxidation of Wang resin derived ethers (Entries 5-7, Table 3.41). 

In the noble metal-catalyzed oxidations described above vicinal diol cleavage is sometimes observed as a side-reaction but never as a main reaction. Oxidative diol cleavage usually involves stoichiometric oxidants such as periodate (Malaprade oxidation) and there is a great need for catalytic procedures employing inexpensive, clean oxidants such as O2 or H2O2. 

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 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). 

Make models of the cis and trans diols. Notice that it is much easier to form a five-membered cyclic periodate from the cis diol A than from the trans diol B. The cis periodate intermediate is of lower energy than the trans periodate intermediate because of the lack of strain in the cis periodate ring. Because any factor that lowers the energy of a transition state or intermediate also lowers AG and increases the rate of reaction, diol cleavage should proceed more slowly for trans diols than for cis diols. 

With a particular poly(vinyl alcohol) sample no periodic acid is consumed, within the limits of analytical aecuracy. This indicates no apparent (1,2-diol) cleavage. However, the viscosity average molecular weight of the sample decreased from 250,000 to 100,0(X), Explain these results in terms of the structures of po y(vinyl acetate) and polyfvinyl alcohol). [The analytical technique is described by P. J. Flory and F. S, Leutner, J. Polym. Set. 3,880 (1948) 5, 267(1950).]... 

Diols are oxidatively cleaved by reaction with periodic acid (HIO4) to yield carbonyl compounds, a reaction similar to the KMnO cleavage of aJkenes just discussed. The sequence of (1) alkene hydroxylation with OsO< j followed by (2) diol cleavage with HIO4 is often an excellent alternative to direct alkene cleavage with ozone or potassium permanganate. 

Starting with geraniol (126), Sharpless asymmetric epoxidation [68] proceeded in 95% yield and with 93% ee (see Scheme 29) [69]. Hydrobromination of the alkene was achieved under standard conditions using NBS in THF and water (5 1) to afford a 64% yield of diastereomeric bromo alcohols (127). Cyclization to the tetrahydropyran diol was accomplished by treating 127 with camphorsulphonic acid in diethyl ether, followed by diol cleavage with sodium periodate to give a mixture of aldehydes 128 and 129. Upon... 

Periodate promoted cleavage of vicinal diols has also been used to prepare monocyclic products. Oxabicyclo[4.2.1]nonadiene 116 derived from diiodoke-tone 77 was subjected to sodium periodate and sodium borohydride reduction to generate 117, Eq. 87. Subsequent elaborations resulted in the stereocontrolled synthesis of oxepine 118, a subunit designed for the assembly of polyether toxins such as ciguatoxin [135]. 

Oxidative Cleavage Reactions. Among the numerous methods for 1,2-diol cleavage there exist only a few that involve catalytic ruthenium reagents, for example Ruthenium(III) Chloride with Sodium Periodate Attempted selective monooxidation of a 1,2-diol to the hydroxy aldehyde with catalytic TPAP and NMO resulted in carbon-carbon bond cleavage to provide the aldehyde (eq 11). Furthermore, attempted oxidation of an anomeric a-hydroxy ester failed instead, in this case decarboxy-lation/decarbonylation and formation of the lactone was observed (eq 12). However, Dimethyl Sulfoxide-Acetic Anhydride provided the required a-dicarbonyl unit. Retro-aldol fragmentations can also be a problem. ... 

Predict the products formed by periodic acid cleavage of the following diols. (a) CH3CH(0H)CH(0H)CH3... 

D-mannitol by diol cleavage with sodium periodate at pH 6 in place... 

Diol cleavage played an important role in natural product structure analysis in the days before instrumental analysis. Understandably, the importance of periodic acid oxidations has diminished somewhat in modern organic chemistry. 

The second method of enzyme electrode preparation is based on the immobilization of glycoenzymes via their glycosidic component [178]. Here the carbohydrate moiety of glycoenzymes is activated by a periodate oxidation cleavage of vicinal diols of the carbohydrate units. The... 

FIGURE 16.74 The vicinal diol cleavage by periodic acid involves a cychc intermediate that breaks down to give a pair of carbonyl compounds. 

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