The oxidative cleavage of 1,2-diols

Cleavage of 1,2-diols using either lead tetra-acetate or sodium metaperiodate is a general reaction which has important preparative applications. 

Cleavage of open-chain symmetrical diols, which must yield a single alde-hydic product, is clearly of most value. The preparation of butyl glyoxylate from dibutyl (+ )-tartrate (Expt 5.77) using lead tetra-acetate in benzene solution is an interesting example. A second example is the cleavage of the 1,2-diol system 

Periodic acid (or sodium metaperiodate) is often the reagent of choice when the substrate is soluble in an aqueous medium, as in the carbohydrate field an example of its use is to be found in Expt 5.117. Sodium metaperiodate supported on silica gel (Section 4.2.55, p. 454) has been found to effectively oxidise water-insoluble a-diols,10f and its value is illustrated in the preparation of hexanedial (Expt 5.78) from trans-cyclohexane-l,2-diol. 

In view of the quantities of benzene (CAUTION) required, the entire preparation must be carried out in the fume cupboard. Place a mixture of 125 ml of pure benzene and 32.5 g (0.123 mol) of dibutyl ( + )-tartrate (1) in a 500-ml threenecked flask, equipped with a Hershberg stirrer (Fig. 2.49) and a thermometer. Stir the mixture rapidly and add 58 g (0.13 mol) of lead tetraacetate (Section 4.2.45, p. 441) in small portions over a period of 20 minutes while maintaining the temperature below 30 °C by occasional cooling with cold water. Continue the stirring for a further 60 minutes. Separate the salts by suction filtration and wash with two 25 ml portions of benzene. Remove the benzene and acetic acid from the filtrate by flash distillation and distil the residue under diminished pressure, preferably in a slow stream of nitrogen. Collect the butyl glyoxylate (2) at 66-69 °C/5 mmHg. The yield is 26g (81%). 

(1) The purified commercial dibutyl (+ )-tartrate, m.p. 22 °C, may be used. It may be prepared by using the procedure described under isopropyl lactate (Expt 5.145). Place a mixture of 75g of (+ )-tartaric acid, lOg of Zerolit 225/H , llOg (135 ml) of redistilled butan-l-ol and 150 ml of sodium-dried benzene in a 1-litre threenecked flask equipped with a sealed stirrer, a double surface condenser and an automatic water separator (cf. Fig. 2.31(a)). Reflux the mixture w th stirring for 10 hours about 21 ml of water collects in the water separator. Filter ol the ion-exchange resin 

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Exercise 16-38 Write mechanisms for the oxidative cleavage of 1,2-diols by lead tetraethanoate and sodium periodate based on consideration of the mechanism of chromic acid oxidation (Section 15-6B). ... 

The oxidative cleavage of 1,2-diols with NaI04 appears to be a powerful method to prepare phosphonylated aldehydes with variable carbon chain lengths. It has been applied successfully to the synthesis of diethyl l-(ethoxycarbonyl)-4-oxobutylphosphonate, a precursor in tlie preparation of glycinoeclepin A, in 70% yield (Scheme 5.41). ... 

Criegee oxidation Cleavage of 1,2-diols (glycols) to the corresponding carbonyl compounds using LTA. 114... 

Oxidative Cleavage of 1,2-Diols. NaI04 is widely used for the oxidative cleavage of a variety of 1,2-diols to yield aldehydes or ketones (eq 1). In this respect, it complements the Lead(IV) Acetate method for oxidation. 1,2-Diols have been shown to be chemoselectively cleaved by NaI04 in the presence of a sulfide group.NaI04 coated on wet silica gel efficiently oxidizes 1,2-diols to the aldehydes (eq 2). This method is particularly useful for the preparation of aldehydes which readily form hydrates, and it is also convenient to conduct because isolation of the product involves simple filtration of the reaction mixture and evaporation. 

Oxidative cleavage of 1,2-diols with periodie acid or with lead tetraacetate gives aldehydes or ketones 23,24,25,26,27,39,44,46. A molecule with a particular functional group can be prepared from molecules containing different functional groups by a series of chemical steps (reactions). This process is called synthesis The new molecule is synthesized from the old one (see Chapter 25) 28, 29, 30, 37, 45, 46, 47, 48. 

The reaction requires 4 to 5 F, and parallel, direct oxidation of (11) cannot be excluded. a-Acetoxycycloalkanones undergo similar cleavage reactions in MeOH-LiCl04. Bond cleavage does not occur for (11) in MeOH-Et4NOTs [13], that is, conditions in which less EGA production is expected (cf Sect. 14.1.2), whereas cleavage of 1,2-diols does take place [21]. 

In the same year an efficient one-pot oxidation and reduction sequence was also described for the cleavage of 1,2-diols to their corresponding primary alcohols [42]. This process was an excellent demonstration of two immobilized incompati-... 

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). 

The readily available catalyst vanadyl bisacelylacetonate when used with r-bulyl hydroperoxide in benzene will oxidize secondary alcohols (Scheme 20) much mote rapidly than primary ones (rate ratio > 100 1), but the other oxidizing prqieities of this system, in particular the epoxidation of allylic alcohols and the cleavage of 1,2-diols might well limit its uses somewhat. ... 

Lead tetraacetate is very frequently used for cleavage of 1,2-diols and preparation of fhe resulting carbonyl compounds. The rate of reaction is highly dependent on the stereochemistry of the substrate. There is usually correlation between the rate of oxidation and the spatial proximity of the hydroxy groups. For example, the rate of the oxidative cleavage of cis-cyclopentane-l,2-diol is much faster than that of trans isomer. It is, however, possible to oxidize trans-l,2-diol to diketone (Scheme 13.51) [72 a]. 

Oxidative deavage of 1,2-diols to carboxylic acids by HP was achieved using catalytic amounts of tungstate and phosphate ions, under acidic conditions [34c,37vj. The reaction was conducted at 90 °C and pH 2 in aqueous solution, with a slight excess of HP with respect to the stoichiometric amount required. A 94% yield of AA was obtained from trans-1,2-cyclohexandiol, and a slightly lower 92% yield from the cis isomer. The reaction proceeded via an initial C—H bond fission of the secondary carbinol to form the related a-ketol, followed by oxidative cleavage of the latter to yield a keto acid intermediate. 

Okamoto, T., K. Sasaki, and S. Oka (1988). Biomimetic oxidation with molecular oxygen. Selective carbon-carbon bond cleavage of 1,2-diols by molecular oxygen and dihydropyridine in the presence of iron-porphyrin catalysts. J. Am. Chem. Soc. 110, 1187-1196. 

The mechanism of this reaction was discussed by the authors (Scheme 4.40). Initially, aldehydes are formed by the PIDA mediated oxidative C-C bond cleavage of 1,2-diols, which are generated from the dihydroxylation of alkenes [142]. Upon the decomposition of ammonium bicarbonate, the aldehydes could be trapped by ammonia to give imines, which would be further oxidized to give nitriles. This reaction shows the efiftciency of the combination of metal-free oxidant and inexpensive nitrogenation agent for the synthesis of nitriles, which should be of great value in further studies. 

A detailed investigation of IBX reactions with various vicinal diols revealed that, depending on the substrate and the reaction conditions, either oxidation to a-ketols or a-diketones, or oxidative cleavage of the C—C bond can occur (20070BC767). In DMSO solutions, IBX oxidatively cleaves strained and stericaUy hindered syn 1,2-diols, while the non-hin-dered secondary glycols are oxidized to a-ketols or a-diketones. The use of trifluoroacetic acid as a solvent leads to an efficient oxidative fragmentation of 1,2-diols of aU types (20070BC767). 

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. 

This heme-dependent enzyme [EC 1.11.1.14], also known as diarylpropane peroxidase, diarylpropane oxygenase, and ligninase I, catalyzes the reaction of 1,2-bis(3,4-dimethoxyphenyl)propane-l,3-diol with hydrogen peroxide to produce veratraldehyde, l-(3,4-dimeth-ylphenyl)ethane-l,2-diol, and four water molecules. The enzyme brings about the oxidative cleavage of C—C bonds in a number of model compounds and also oxidizes benzyl alcohols to aldehydes or ketones. 

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