Oxidative cleavage of α-hydroxyketones

Tetrahedron Letters 50 (2009) 5399–5402
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The oxidative cleavage of vicinal diols, a-hydroxyketones, and related functionalities is a common synthetic procedure and various reagents are available to perform this reaction, such as sodium bismuthate,1 iodo triacetate,2 manganic pyrophosphate,3 KHSO5,4 calcium hypochlorite,5 basic hydrogen peroxide,6 methylrhenium trioxide,7 Bi/O2,8 sodium percarbonate,9 and vanadium-based HPA and dioxygen.10 However, the most versatile reagents for this purpose are sodium metaperiodate,11 and lead tetraacetate.12–14
Usually sodium metaperiodate is used in aqueous solutions, because the effectiveness of this oxidant in organic solvents is very limited due to its insolubility.15 Lead tetraacetate has been used in non-aqueous media to accomplish the same types of reactions effected by periodates with water-soluble compounds.15 On the
other hand, this reagent is difficult to store and handle, non-environmentally friendly and, being more reactive, can afford undesired oxidation byproducts.
Aiming to expand the versatility of sodium metaperiodate as an oxidating reagent in organic media, and to overcome the solubilityissues, variations of a silica gel-supported sodium metaperiodate reagent have been disclosed, to promote oxidative cleavage of 1,2 diols, and oxidation of hydroquinones and sulfur-containing compounds.16–18 Usually the sodium periodate is adsorbed on silica gel, and stirred with the starting material in dichloromethane, ether, or benzene.
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One of the conditions described in the reference paper (NaIO4/SiO2/toluene) was applied to a mixture of alpha-hydroxyketone and TMS protected alpha-hydroxyketone shown below.
Surprisingly, only alpha-hydroxyketone was cleaved. The TMS protected alpha-hydroxyketone survived.
compared with HIO4 in Et2O, this condition (NaIO4/SiO2/toluene) is more neutral.

preparation of Dess Martin reagent

recently made about 50 g of it.
here is the detail.

1. oxone 2 eq. and 2-iodobenzylacid? 1 eq. mixed together with deionized water.
stirred at 70-73C for about 4 hr. during the stirring, the insoluable iodoacid will get into the water solution. Finally a nearly clear solution will be seen with some precipitation on the bottom. good stirring is necessary.

2. cool the temp down to 0-5C for 2hr, filter out the white precipitation. wash with acetone.
The ibx is potencially explosive, it is stable at rt and should be dried at rt and 1 atm.

3. pour in Ac2O and catalytic amount of psOH-H2O solid. heated to 80C for 3 hr, a clear solution resulted. cooled it down to 0-5 C, then liquid filtered. washed with ether.
also explosive, dried in vacuo briefly.
stored in freezer.