Meta oxides with alcohols

There are a variety of stoichiometric oxidants that can be used in conjunction with 2,2,6,6-tetramethylpiperdine 1-oxyl (TEMPO), including TCCA, iodobenzene diacetate, meta-chloroperbenzoic acid (m-CPBA), sodium bromite, sodium hypochlorite, and i V-cIiIontsuccinimidc. TEMPO can be used to oxidize primary alcohols to aldehydes or carboxylic acids, based on reaction conditions. A particularly attractive feature is that the product is usually isolated quite pure after concentration of the organic layer. 

The final steps in the conversion of (-)-ll-methoxytabersonine to (-)-vindoline (Scheme 13.53) involved benzeneseleninic anhydride [(C6H5Se0)20j oxidation followed by a second oxidation with meta-chloroperbenzoic acid (MCPBA) in the presence of sodium bicarbonate (NaHCOs). Without isolation, but with adjustment of the pff, reductive A-methylation of the indoline was effected with formaldehyde (ff2CO) addition to the imine, followed by sodium cyanoborohydride (NaBHsCN) reduction. Finally, selective acetylation of the secondary hydroxyl necessary to produce (-)-vindoline (in the presence of the tertiary alcohol) was accomplished with acetic anhydride-containing sodium acetate. 

Vanadium pentoxide dissolves in acids, both organic and inorganic, to form vanadyl or unstable vanadic salts,7 and in alkalis to produce ortho-, pyro-, meta-, and poly-vanadates. The physico-chemical changes involved when vanadium pentoxide is heated with various basic oxides in the powder state have been investigated by Tammann.8 On being digested with liquid ammonia slow absorption of ammonia takes place the composition of the product has not been definitely established.9 The oxide also dissolves in alcohols to produce esters,10 and combines with methylamine and ethylamine to form compounds of the type 2(R.NHB).V205, where R represents the alkyl radical.11... 

The intermediate metaphosphate/phosphonate can then be made to react with ethylene oxide to effect the insertion of ethyleneoxy units into the P-O-P linkages. If a limited amount of water or an alcohol is added to the meta intermediate, the resultant oligomer can be produced with a controlled hydroxyl functionality (11, 12). An example of a functional oligomer made this way is the following ... 

Although significant improvements have been made in the synthesis of phenol from benzene, the practical utility of direct radical hydroxylation of substituted arenes remains very low. A mixture of ortho-, meta- and para-substituted phenols is typically formed. Alkyl substituents are subject to radical H-atom abstraction, giving benzyl alcohol, benzaldehyde, and benzoic acid in addition to the mixture of cresols. Hydroxylation of phenylacetic acid leads to decarboxylation and gives benzyl alcohol along with phenolic products [2], A mixture of naphthols is produced in radical oxidations of naphthalene, in addition to diols and hydroxyketones [19]. 

In contrast to the lack of selectivity observed in the TS-1 catalyzed oxidation of 3-penten-2-ol (1) (Eqn. 21.5), the oxidation of 1 with tert-butyl hydroperoxide (TBHP) over Cr-PILC gave the unsaturated ketone, 3, in 82% yield (Eqn. 21.13)42 while the oxidation of 1 over a vanadium pillared montmorillonite (V-PILC) gave the epoxy alcohol, 2, in 94% yield.43 V-PILC, however, does promote the oxidation of primary benzyl alcohols to the acids with tert-butyl hydroperoxide. This reaction exhibits shape selectivity in that para-substituted benzyl alcohols are oxidized while the ortho- and meta- substituted species are essentially inert (Eqn. 21.14).44... 

Resorcinol (Figure 24.1), also known as resorcin, meta-dihydroxybenzene, 1,3-dihydroxybenzene, and 1,3-ben-zenediol, has a molecular weight of 110.11 and a relative density of 1.272. It is slightly more acidic than phenol, with a pKj of 9.15. It is soluble in water, alcohol, ether and glycerol. It comes in the form of white needle-shaped crystals. Resorcinol crystals oxidize easily, and turn pink on contact with light, air or iron. 

SODIUM META-ALUMINATE (1302-42-7 11138-49-1) Aqueous solution is a strong base. Incompatible with organic anhydrides, acrylates, alcohols, aldehydes, alkylene oxides, substituted allyls, eellulose nitrate, cresols, caprolactam solution, chlorocarbons, epichloro-hydrin, ethylene diehloride, isocyanates, ketones, glyeols, nitrates, phenols, vinyl acetate. Exothermic decomposition with maleic anhydride. May increase the explosive sensitivity of nitromethane. Attacks aluminum, copper, tin, and zine. 

Based on the ability of Pd(OAc)2 to accelerate the [2,3]-rearrangement of amine iV-oxide 114, we explored chiral palladium(ll) salts to catalyze the enantioselective rearrangement. When we treated amine iV-oxides 116 with Pd(OAc)2 and chiral phosphoramidite 118, chiral O-allylhydroxylamines 117 were isolated in 80-85% ee (Scheme 1S.28V Subsequent optimization revealed the beneficial effect of methanol and meta-chlorobenzoic acid (m-CBA) as additives, allowing the isolation of chiral nonracemic O-allylhydroxylamines 117 with greater than 90% enantioenrichment. This palladium-catalyzed enantioselective [2,31-rearrangement can tolerate a wide variety of functional groups in the amine N-oxide substrate. For example, we can synthesize chiral allylic hydrojq lamine products with reactive functional groups such as alcohols and aldehydes, which are inconpatible with many other methods for the synthesis of chiral alcohol derivatives. 

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