Sodium metaperiodate oxidant

Dithiole-2-one (60), which can be readily transformed into its thio- or seleno-carbonyl derivatives, is a key intermediate for the synthesis of tetrathiafulvalene (Scheme 13)[31]. We first anticipated that compound 57, a Michael addition product of xanthate 54 to vinyl sulfoxide, might be an ideal intermediate for the synthesis of 60 via cyclization under Pummerer rearrangement conditions. However, although Michael addition of dithiocarbamate 53 to vinyl sulfoxide proceeded smoothly to yield compound 55, the addition reaction with xanthate 54 failed. We then turned to the alkylation approach. Xanthate 54 was alkylated smoothly with 56, which served as the synthetic equivalent of the vinyl sulfoxide, in ethanol under sonication in 90% yield [32]. Cyclization of 57 under Pummerer rearrangement conditions in the presence of trifluoroacetic acid afforded 58 in 79% yield. Sodium metaperiodate oxidation gave the unstable sulfoxide 59 which underwent thermal elimination to yield 60 in refluxing benzene in moderate yield. 

Begonia tuberhybrida It was readily prepared by sodium metaperiodate oxidation of cucurbitacin D diacetate (53). 

This result suggests an exclusive Z(0)-enolate geometry for these boron enolates. Moreover, the ratio of 7 to 8 becomes impressively high with increasing size of the boron ligands. Desilylation and sodium metaperiodate oxidation of 7 yields the syn j5-hydroxy-a-methyl-carboxylic acids 9, which are fundamental structural units found in numerous natural products of propionate origin. It is recommended by the authors that 6a be used for aldehydes with an a-substituent and that 6c be used for aldehydes carrying no a-substituent (Scheme 1) [3]. 

The partial synthesis of the furan ring in havanensin-type compounds has been accomplished by sodium metaperiodate oxidation of turreanthin in the presence of perchloric acid (Scheme 4). Execution of the apo rearrangement as previously described then led to the partial synthesis of a simple havanensin derivative 36, 39). It is not known if the biosynthesis goes by this route or by an alternative following the more usual limonoid pattern of an oxide rearrangement 81). 

Sulfoxides Produced by Sodium Metaperiodate Oxidation of the Corresponding Sulfides - ... 

When the desired product is a sulfoxide sodium metaperiodate (NaI04) is an ideal reagent It oxidizes sulfides to sulfoxides m high yield but shows no tendency to oxidize sulfoxides to sulfones... 

Oxidation of 4 ten butylthiane (see Problem 16 23 for the structure of thiane) with sodium metaperiodate gives a mixture of two compounds of molecular formula CpHigOS Both products give the same sulfone on further oxidation with hydrogen peroxide What is the relationship between the two compounds ... 

We therefore carried out periodate oxidation of triose reductone in dilute solutions using sodium metaperiodate as the oxidizing agent (55,56), Triose reductone could react with periodate according to the following reaction sequence ... 

Figure 1. Oxidation of 2-deoxy-D-glucose (6 10 4M) with sodium metaperiodate (6.6 10 SM) in 0.1N H2SO4 (curve A) and in unbuffered solution (curve...

Table I. Oxidation of Deoxy Sugars and Related Compounds (6 10 M) in 0.1 N H2SOu at +4°C. with Sodium Metaperiodate (6.6 10 sM).

Figure 3. Oxidation of (1 i.)-l,2,4/3,5-cyclohexanepentol (curve A minutes Curve C hours) and of (+)-quercitol (curve B minutes curve D hours) with sodium metaperiodate (c.f. Table I).

Figure 4. Periodate uptake (10f) and malonaldehyde formation (MA) during the oxidation of (1 d)-1,2,5/3,4-cyclohexanepentol with sodium metaperiodate...

Thioamsole, oxidation, by dinitrogen tetroxidc, 46, 80 by hydrogen peroxide, 46, 80 by lead tetraacetate, 46, 80 reaction with sodium metaperiodate to form methvl phenyl sulfoxide, 46,75... 

Desilylation of the major jjw-isomer, followed by oxidative cleavage with sodium metaperiodate, liberates the 3-hydroxy-2-methyl carboxylic acids. The immolative character of this method, i.e., the destruction of the chiral auxiliary reagent in the final glycol cleavage, is a drawback. 

Oxidation of phenyl hexyl sulphide with sodium metaperiodate gave also only a trace amount of the corresponding sulphoxide72. On the other hand, Hall and coworkers73 prepared benzylpenicillin and phenoxymethyl penicillin sulphoxides from the corresponding benzyl esters by oxidation with sodium metaperiodate in dioxane solution with a phosphate buffer. A general procedure for the synthesis of penicillin sulphoxides was reported later by Essery and coworkers74 which consists in the direct oxidation of penicillins or their salts with sodium metaperiodate in aqueous solution at pH 6.5-7.0. 1-Butadienyl phenyl sulphoxide 4475 and a-phosphoryl sulphoxides 4576 were also prepared by the same procedure. 

Alumina supported sodium metaperiodate, which can be prepared by soaking the inorganic support with a hot solution of sodium metaperiodate, was also found to be a very convenient reagent for the selective and clean oxidation of sulphides to sulphoxides79. The oxidation reaction may be simply carried out by vigorous stirring of this solid oxidant with the sulphide solution at room temperature. As may be expected for such a procedure, solvent plays an important role in this oxidation and ethanol (95%) was found to be... 

Silica gel supported sodium metaperiodate was used for the selective oxidation of dibenzyl sulphide80. Metaperiodate anion soaked on strongly basic-ion-exchange resins Amberlite IRA-904 or Amberlyst A-26 was found to be able to oxidize sulphides into the corresponding sulphoxides in 82-99% yield81. 

In contrast to the asymmetric procedures discussed above, the metal-catalyzed oxidation of alkyl aryl sulphides by t-butylhydroperoxide carried out in a chiral alcohol gives rise to chiral sulphoxides of low optical purity290 (e.e. 0.6 9.8%). Similarly, a very low asymmetric induction was noted when prochiral sulphides were oxidized by sodium metaperiodate in chiral alcohols as solvents291. 

Much higher asymmetric induction was observed in the two-phase oxidation of simple alkyl aryl and diaryl sulphides296, substituted alkyl aryl sulphides297 and dithioacetals of formaldehyde298 by sodium metaperiodate in the presence of proteins such as bovine serum y-globulin and egg albumin. Optical purities of the sulphoxides so formed ranged between 20 and 85%. 

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