Hydroxy and Oxo Groups

Oxidation reactions include electron abstraction, introduction of hydroxy and oxo groups, and also rearrangement of the carbon skeleton. 

The reaction proceeds well in the presence of side chains with ether or acetal protecting groups, thus providing a convenient route to methylenecyclopropanes with hydroxy and oxo groups. The synthesis and subsequent hydrolysis of l,la,6,6a-tetrahydro-l-methylene-spiro[cyclopropa[c ]indene-6,2 -[l, 3]dioxolane] (10) provides an illustrative example. ... 

Bicyclic Systems with Two Ring Junction Nitrogen Atoms 8.31.9.9 Hydroxy and Oxo Groups... 

Amino and Other Nitrogen Groups. 7.5 Hydroxy and Oxo Groups. 7.6 Sulfur-Linked Groups. 7.7 Halogen Atoms... 

Oxo-, hydroxy and amino groups activate ortho and para positions toward attack by halogens and this far outweighs the deactivating effect of the pyridine nitrogen. Consequently, these compounds are much more reactive than the foregoing examples and this... 

Purine has a pK value of 2.39. Thus, the molecule is more basic than pyrimidine (pK = 1.31), but less basic than imidazole (6.99). Electron-withdrawing groups decrease, electron-donating groups increase basicity. Hydroxy and sulfanyl groups which form oxo or thioxo tautomers weaken the acidic properties. The pK values shown in Tables 3-5 were determined spectropho-tometrically, potentiometrically, by NMR, etc (cf. also Table 15, p 320 ff). 

Oxy includes hydroxy (and hydroxyalkyl), alkoxy (and alkoxyalkyl), aryloxy, acyloxy (e.g., acetoxy), and oxo groups. 

The substituent effect on the tautomeric equilibrium in solution has been studied using experimental pKa values and UV spectra (in water at 20 °C) of several 4(177)-pyridones and their N- and O-fixed derivatives. It was concluded that most of the factors affecting the tautomerism of 4(l/7)-pyridones are due to the electronic effect, including steric effect, of the substituents in the 2-position. Thus, the proportion of the hydroxy form increases on introduction of an electron-withdrawing group into the 2-position. For example, 5-methoxy-4(l/7)-pyridones with a methyl, hydroxymethyl, and methoxymethyl groups in the 2-position exist essentially in the pyridone form however, 2-methoxycarbonyl-substituted derivative exists as a mixture of hydroxy and oxo form in water (77BCJ710). The effect of substituents in the 3-position... 

Friedo-oleane triterpenes with a hemiacetal 24-hydroxy-3-oxo grouping are exclusive to the Celastraceae and several have been isolated from South American species. It has been proposed that these compounds may be intermediates in the biogenetic pathway to the Celastraceae triterpene quin ones. 

Amongst additionally functionalized aminoalkyl phosphonic acids, of which the hydroxy- and oxo-derivatized compounds are the more important, (haloaminoalkyl)-phosphonic acids have been very seldom reported. In the reactions between trialkyl phosphites and the aminotetrachloroethanes 161, the integrity of the trichloromethyl group is, surprisinglv, retained, with the (l-amino-2,2,2-trichloroethyl)phosphonates 162 as the products, e.g. with R = Such compounds may be reduced by Bu3SnH, but the... 

The most important furans in major food commodities are 4-hydroxy-2H-furan-3-ones (8-159), which are characterised by a planar arrangement of molecules and the same configuration of the enol, hydroxyl and oxo groups. Furanones occur as racemic mixtures because of their keto-enol tautomerism (Figure 8.71). Some other compounds have analogous structures as furanones, such as maltol, 3-hydroxy-2H-pyran-2-one and cyclopentenolones. All compounds with this structure resemble more or less the caramel... 

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