Vicinal diols oxidative cleavage

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)... 

The reaction is based, on the one hand, on the oxidative cleavage of vicinal diols by lead(IV) acetate and, on the other hand, on the reaction of dichlorofluorescein with lead(IV) acetate to yield a nonfluorescent oxidation product. The dichlorofluorescein only maintains its fluorescence in the chromatogram zones where the lead(IV) acetate has been consumed by the glycol cleavage reaction [1],... 

The oxidative cleavage of the central carbon-carbon bond in a vicinal diol 1, by reaction with lead tetraacetate or periodic acid, yields two carbonyl compounds 2 and 3 as products. 

In theory, periodate oxidation could have given a clear-cut answer as to the composition of the isomeric mixture of deoxy ribose phosphates. The 4-phosphate (73), devoid of vicinal diol groups, should be resistant to periodate the 3-phosphate (74) should reduce one and only one molar equivalent of the oxidant and yield one molar equivalent of both formaldehyde and the phosphorylated dialdehyde (75), whereas the 5-phosphate (76) could be expected to reduce one molar equivalent of periodate relatively rapidly, followed by a slower overoxidation reaction owing to the oxidation of malonaldehyde, formed as a result of the glycol cleavage. 

We have developed an efficient and practical method for clean oxidation of starch (21-23) resulting in the oxidation of primary alcohol function in Ce position and the cleavage of vicinal diols in C2 and C3 position (Figure 30.2). We used small amounts of cheap iron tetrasulfophthalocyanine catalyst, pure water as reaction medium and H2O2 as clean oxidant to achieve a one-pot conversion of starch resulting in the introduction of aldehyde and carboxyl functions in polymer chains. The iron content... 

The favored oxidative cleavage of a primary-secondary over a primary-tertiary vicinal diol grouping has been utilized in the synthesis of branched-chain sugar derivatives.482,483... 

The nickel hydroxide electrode resembles in its applications and selectivity the chemical oxidant nickel peroxide. The nickel hydroxide electrode is, however, cheaper, easy to use and in scale-up, and produces no second streams/ waste- and by-products [196], Nickelhydroxide electrode has been applied to the oxidation of primary alcohols to acids or aldehydes, of secondary alcohols to ketones, as well as in the selective oxidation of steroid alcohols, cleavage of vicinal diols, in the oxidation of y-ketocarboxylic acids, of primary amines to nitriles, of 2,6-di-tert-butylphenol to 2,2, 6,6 -tetra-rert-butyldiphenoquinone, of 2-(benzylideneamino)-phenols to 2-phenyloxazols, of 1,1-dialkylhydrazines to tetraalkyltetrazenes. For details the reader is referred to Ref. [195]. 

The Mn + complexed ions appear to be the most selective and efficient initiator system for grafting to polysaccharides so far described. The mechanism of the initiation reaction has been studied in our laboratories by model experiments and ESR spectroscopy. There are two possible reactions indicated. Bond cleavage of a vicinal diol according to reaction (22) is one possibility. Another and faster reaction with Mn3+ giving radicals appears to be oxidation of aldehyde groups (24) to alkoxy radicals ... 

The formation R-CO radicals from glucose is verified by spintrapping experiments with tert-butyl-nitroxide and recorded ESR spectra for the resulting compound. Ring-closed vicinal diols indicate fast bond cleavage by Mn + oxidation and efficient initiation of vinyl polymerization., ... 

There are fewer examples of this for such Ru-catalysed oxidations than for C-H activation, cleavage of the C-C bond in diols being the main example [111]. Optically pure D- and L-glyceric acids were made by cleavage of vicinal diols or of a-hydroxy acids by RuCl3/aq. Na(ClO) pH 8, e.g. l,2 5,6-di-0-isopropylidene-D-mannitol to 2,3-0-isopropylidene-D-glyceric acid (Fig. 4.6) [112],... 

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. 

Recently, heterogeneous catalytic systems were described41 that employ molecular oxygen for the liquid phase oxidative cleavage of vicinal diols. Although the catalysts appear to be mixed metal oxides rather than supported metals the method resembles closely the noble metal-catalyzed oxidations described above, hence their inclusion in this section. 

There are several methods reported in the literature for transforming vicinal diols into ct-diketones while avoiding the risk of C-C bond cleavage.26 Examples include the standard Swem conditions (dimethyl sulfoxide and oxalyl chloride followed by triethylamine), or the use of DMSO activated by acetic anhydride, pyridine-sulfur trioxide complex, or dicyclohexylcarbodiimide (Mq/J-att oxidation). Diones are also obtained by treatment with benzalacetone as a hydride acceptor in the presence of catalytic amounts of tris(triphenylphosphine)ruthenium dichlonde [(PPh RuCFl.27 Recent developments include the use of w-iodoxyben/.oic acid28 or the oxoammonium salt of 4-acctamidoletramethylpipcridine-1-oxyl and y -toluencNulfonic acid.29... 

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