Oxidative of diols

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),... 

Bu2Sn=0 Selective oxidation of 1,2-diols to a-hydroxy ketones was electro-chemically achieved in a double mediatory system consisting of dialkyl tin oxide and the bromide ion (Fig. 3) [34]. 

Regioselective oxidation of 1,2-diols.1 The oxidation of di-secondary glycols to acyloins (5, 188) can be extended to oxidation of other glycols. Thus the stan-nylene of 1 is oxidized by bromine to 2 in high yield. The reaction is regioselective with unsymmetrical diols (3 — 4). 

Because of the mildness of Fetizon s reagent and its sensitivity to minor structural features, this oxidant is particularly well-suited for the mono oxidation of symmetric diols7 and for the oxidation of 1,2-diols in which one of the alcohols is tertiary.8... 

Among examples of applications of polarography to the study of homogeneous kinetics, the oxidation of 1,2-diols with periodic acid (21) can be mentioned. In this reaction the decrease in the concentration can be followed (Fig. 10). Furthermore, it can be confirmed, whether all the... 

C-H Wong, JR Matos. Enantioselective oxidation of 1,2-diols to L-a-hydroxy acids using co-immobilized alcohol and aldehyde dehydrogenases as catalysts. J Org Chem 50 1992-1994, 1985. 

The anodic oxidation of 1,2-diols and their ether derivatives is a simple and clean mediod for the fission of glycols to the corresponding carbonyl compounds (equation 1). The reaction is carried out using carbon electrodes in methanol containing tetraediylammonium p-toluenesulfonate as a supporting electrolyte.2 ... 

KINETICS AND MECHANISM OF OXIDATION OF 1,2-DIOLS The stoichiometry of the oxidation of 1,2-diols is... 

Two types of kinetics have been observed in the oxidation of 1,2-diols by periodate. The first of these, exemplified by ethane-1,2-diol, is of a mixed-order type, and is consistent with the reversible formation of the cyclic diester as an intermediate. The second type, exemplified by pinacol, is second-order kinetics, the reaction showing general acid-base catalysis and a complex dependence of rate on pH. 

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. 

The few kinetic studies of the oxidation of 1,2-diketones indicate that the mechanism differs from that found for the oxidation of 1,2-diols, and that, contrary to earlier suggestions, the reaction does not proceed via a hydrate of the diketone. Shiner and Wasmuth studied the oxidation of butane-2,3-dione,... 

Dahlgren and Reed ). Shiner and Wasmuth suggest that the oxidation of 1,2-diketones proceeds via a cyclic periodate ester, similar to that postulated for the oxidation of 1,2-diols, but formed by nucleophilic attack of periodate on carbon, viz. 

Only one kinetic study has been reported. The oxidation of 3-hydroxy-3-methyl-butane-2-one is second-order with a rate maximum at pH 8 (Bunton and Shiner ). The same authors carried out an experiment at pH 8 which shows that the C-OH bond is not broken, as in the oxidation of 1,2-diols. The mode of attack on the carbonyl group is probably nucleophilic at the carbon atom, as in the oxidation of 1,2-diketones. 

S)-2-hydroxy propionic acid (lactate)11321 and for the kinetic resolution of racemic 2-hydroxy acids[127, 131], but also for selective oxidations of 1,2-diols such as ethylene glycol (Fig. 16.2-30). 

Silver oxide can also oxidize primary alcohols directly to the acid, as in the oxidation of 1-dodecanol to dodecanoic acid. Oxidation of 1,2-diols is accompanied by cleavage to the diacid (sec. 3.7.C), as in the conversion of 1,2-cyclohexanediol to adipic acid in 89% yield. ... 

Oxidation of 1,2-diols. a-Diketones are produced by the reaction of glycols with... 

An alternative method for the formation of aldehydes or ketones makes use of the complexes formed from a methyl sulfide with chlorine or A-chlorosuccinimide (NCS), in what is called the Corey-Kim oxidation. With dimethyl sulfide the salt 28 is generated and reacts with the alcohol to give the alkoxysulfonium salts and hence, on treatment with a base, the carbonyl compound. This reaction has fovmd particular application in the oxidation of 1,2-diols in which one alcohol is tertiary, to give a-hydroxy-aldehydes or ketones without rupture of the carbon-carbon bond. For example, the aldehyde 32 is formed in good yield from the diol 31 using dimethyl sulfide and NCS followed by addition of triethylamine (6.29). This transformation is thought to depend on the preferential five-membered transition... 

The DMP oxidation of 1,2-diols generally cleaves the glycol C—C bond, as illustrated by the synthesis of tricyclic enol ether 883 from diol 882 via tandem 1,2-diol cleavage-intramolecular cycloaddition (Scheme 3.355) [1220]. 

Wong and Matos (1985) reported a stereospecific oxidation of 1,2--diols to a-hydroxy carboxylic acids via a-hydroxy aldehydes.. The trick employed here is to coimmobilize HLADH and aldehyde dehydrogenase (AldDH) into polyacrylamide. The former enzyme oxidizes the diol to the corresponding a-hydroxy aldehyde, which is further oxidized to the a-hydroxy carboxylic acid by the latter enzyme (Scheme 34). After 40 % conversion of the substrates, enantiomer... 

Wong CH, Matos JR (1985) Enantioselective oxidation of 1,2-diols to L-a-hydroxy acids using coimmobilized alcohol and aldehyde dehydrogenase as catalysts. J Org Chem 50 1992-1994 Yasui S, Nakamura K, Ohno A, Oka S (1982) Reduction by a model of NAD(P)H. 36. First and direct evidence for the multi-step mechanism. Bull Chem Soc Jpn 55 196-199 Yasui S, Nakamura K, Ohno A (1983) Reduction by a model of NAD(P)H. 42. Direct evidence for one electron transfer mechanism in the reduction of arenediazonium salts. Tetrahedron Lett 24 3331-3334 Yasui S, Nakamura K, Ohno A (1984) Reduction by a model of NAD(P)H. 45. Mechanism for the dediazonation of arenediazonium salts initiated by one-electron transfer from an NAD(P)H-model. J Org Chem 49 878-882... 

Minato D, Arimoto H, Nagasue Y, Demizu Y, Onomura O (2008) Asymmetric electrochemical oxidation of 1,2-diols, aminoalcohols, and aminoaldehydes in the presence of chiral copper catalyst. Tetrahedron 64 6675-6683... 

Maki T, Fukae K, Hasegawa H, Ohishi T, Matsumura Y (1998) Selective oxidation of 1,2-diols by electrochemical method using organotin compound and bromide ion as mediators. Tetrahedron Lett 39 651-654... 

Oxidation of 1,2-Diols. CuBr2/LiO Bu oxidatively cleaves rerr-l,2-diols at ambient temperature, yielding ketones. This method is particularly useful for oxidizing frans-cyclic diols, where NaI04 is ineffective and toxic Pb(OAc)4 performs the reaction only slowly. ... 

Scheme 26 Regioselective oxidation of 1,2-diols using organotin catalysts. ...

William JM, Kuriyama M, Onomura O. Boronic acid-catalyzed selective oxidation of 1,2-diols to a-hydroxy ketones in water. Adv Synth Catal. 2014 356 934-940. 

---