Sodium oxidative cleavage with

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. 

Transformation of the amino nitriles to the corresponding amino acids, with removal of the dioxane ring, is carried out in two steps. Treatment with concentrated hydrochloric acid results in the hydrolysis of both the nitrile and the acetal group, and in cyclization to the corresponding 3-substituted 5-hydroxyniethyl-3-methyl-2-oxo-6-phenylmorpholinc hydrochlorides. Oxidative cleavage with 2 N sodium hydroxide solution, air and Raney nickel at 120 CC (ca. 30 h) delivers the hydrochlorides of the free a-methylamino acids in high yield. 

Preparative Methods prepared in two steps from commercially available L-gulonolactone via ketalization and oxidative cleavage with sodium periodate at pH 5.5. Also obtained from l-ascorbic acid via (i) ketalization, reduction (lithium aluminum hydride) and oxidative cleavage (sodium periodate), or (ii) ketalization and oxidative fragmentation using hydrogen peroxide and hypochlorous acid. ... 

Preparative Methods prepared in two steps from o-mannitol via bis-ketalization to l,2 5,6-bis-( -(l-methylethylidene)-D-mannitol, followed by oxidative cleavage with sodium periodate in dichloromethane. Classically obtained from o-mannit-ol by bis-ketalization and oxidative cleavage with lead tetraacetate. Bis-ketalization has been accomplished under a range of conditions " a comparative study of the most commonly employed methods has appeared. ... 

Scheme 5.1. General mode of oxidative cleavage with sodium bismuthate.

Sodium metaperiodate has been applied as the stoichiometric oxidant in numerous transition metal catalyzed oxidations. Of particular use is a one-pot oxidative cleavage of olefins to aldehydes by the Os04-NaI04 catalytic system, as exemplified in Scheme 3.374 [1362]. This oxidative cleavage, with some modifications. 

Reductive cleavage with lithium aluminium hydride-aluminium chloride, or with sodium cycloborohydride-hydrochloric acid, or with aluminium chloride-trimethylamine, of endo-3t4-0-(4-methoxybenzylidene) acetal rings of 1,6-anhydro- -D-galactopyranose derivatives gives predominantly the axial 3-0-(4-0-methoxybenzyl)ether derivatives. Oxidative cleavage with DDQ affords the axial 3-0-(4-inethoxybenzoyl)... 

Finally, additional multifunctional cleavage strategies are possible. Oxidative cleavage with hydrogen peroxide and sodium hydroxide can be used to generate phenols (Table 1.18, Entry 6) ° while rhodium(I)-mediated 1,2-addition to aldehydes provides secondary alcohols (Table 1.18, Entry 7) and 1,4-addition to a,p-unsaturated ketones yields ketones (Table 1.18, Entry 8). ... 

Obtained synthetically by one of the following processes fusion of sodium ben-zenesulphonate with NaOH to give sodium phenate hydrolysis of chlorobenzene by dilute NaOH at 400 C and 300atm. to give sodium phenate (Dow process) catalytic vapour-phase reaction of steam and chlorobenzene at 500°C (Raschig process) direct oxidation of cumene (isopropylbenzene) to the hydroperoxide, followed by acid cleavage lo propanone and phenol catalytic liquid-phase oxidation of toluene to benzoic acid and then phenol. Where the phenate is formed, phenol is liberated by acidification. 

Alicyclic hydroxamic acids undergo several specific oxidative cleavage reactions which may be of diagnostic or preparative value. In the pyrrolidine series compounds of type 66 have been oxidized with sodium hypobromite or with periodates to give y-nitroso acids (113). Ozonolysis gives the corresponding y-nitro acids. The related cyclic aldonitrone.s are also oxidized by periodate to nitroso acids, presumably via the hydroxamic acids.This periodate fission was used in the complex degradation of J -nitrones derived from aconitine. 

As inert as the C-25 lactone carbonyl has been during the course of this synthesis, it can serve the role of electrophile in a reaction with a nucleophile. For example, addition of benzyloxymethyl-lithium29 to a cold (-78 °C) solution of 41 in THF, followed by treatment of the intermediate hemiketal with methyl orthoformate under acidic conditions, provides intermediate 42 in 80% overall yield. Reduction of the carbon-bromine bond in 42 with concomitant -elimination of the C-9 ether oxygen is achieved with Zn-Cu couple and sodium iodide at 60 °C in DMF. Under these reaction conditions, it is conceivable that the bromine substituent in 42 is replaced by iodine, after which event reductive elimination occurs. Silylation of the newly formed tertiary hydroxyl group at C-12 with triethylsilyl perchlorate, followed by oxidative cleavage of the olefin with ozone, results in the formation of key intermediate 3 in 85 % yield from 42. 

Osmium tetroxide used in combination with sodium periodate can also effect alkene cleavage.191 Successful oxidative cleavage of double bonds using ruthenium tetroxide and sodium periodate has also been reported.192 In these procedures the osmium or ruthenium can be used in substoichiometric amounts because the periodate reoxidizes the metal to the tetroxide state. Entries 1 to 4 in Scheme 12.18 are examples of these procedures. Entries 5 and 6 show reactions carried out in the course of multistep syntheses. The reaction in Entry 5 followed a 5-exo radical cyclization and served to excise an extraneous carbon. The reaction in Entry 6 followed introduction of the allyl group by enolate alkylation. The aldehyde group in the product was used to introduce an amino group by reductive alkylation (see Section 5.3.1.2). 

Oxidative cleavage of alkenes using sodium periodate proceeds effectively in a monophasic solution of acetic acid, water, and THF with very low osmium content or osmium-free. The orders of reactivity of alkenes are as follows monosubstituted trisubstituted >1,2 disub-stituted > 1,1-disubstituted > tetrasubstituted alkynes.100 Cleavage with polymer-supported OSO4 catalyst combined with NaI04 allows the reuse of the catalyst.101... 

Reaction of nitromethane and monosaccharide-derived dialdehydes is a useful tool that has been broadly used for the preparation of nitro and amino sugars, and carbocycles.30 Dialdehydes can easily be obtained by oxidative cleavage of conveniently protected monosaccharides with sodium periodate. Their subsequent Henry reaction with a nitroalkene, commonly nitromethane, usually gives isomeric mixtures that require the isolation of the major isomer.31 Thus, treatment of the D-ribose derivative 27 with sodium periodate gave dialdehyde 28, which was subjected to a Henry reaction with nitromethane, to afford nitrosugar 29 as an epimeric mixture (Scheme 11).32... 

Nitrocyclohexadiene 93a reacted with 4.0 equivalents of cyclopentadiene in toluene at 110°C for 96 h, producing the 10-glyco-l-nitrotricyclo[5.2.2.02,6]undeca-3,8-diene 96a in 70% yield. Subsequent treatment with potassium carbonate in a methanol-water (9 1) solution followed by oxidative cleavage of the sugar side chain with sodium metaperiodate afforded aldehyde 96c. Reduction of the aldehyde with sodium borohydride produced alcohol 96d. 

Efficient cleavage of A.A-dimethylhydrazones to yield the parent ketones (>90%) is effected under neutral conditions with tetra-n-butylammonium persulphate [40], The procedure is particularly useful for compounds with acid-sensitive substituents, e.g. vinyl or ketal groups. Similarly, reaction times for the oxidative cleavage of semicarbazones with sodium nitrite or nitrate/trimethylsilyl chloride are reduced by the addition of benzyltriethylammonium chloride [41]. 

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