Halo-hydroxylation

Oxidation and Halo-hydroxylation of Monoterpenes with Chloroperoxidase from Leptoxyphium fumago... 

Figure 11.3 Stereoselective halo-hydroxylation of the monoterpene hydrocarbon (IS)-(+)-3-carene by CPO in the presence of hydrogen peroxide and halide ions (X — CC, Br or C).

Kaup, B.A., Piantini, U., Wust, M. and Schrader, J., Monoterpenes as novel substrates for oxidation and halo-hydroxylation with chloroperoxidase from Caldariomyces fumago. Appl. Microbiol. Biotechnol., 2007, 73, 1087-1096. 

Various groups on the aromatic nucleus including halo, hydroxyl, alkoxyl, and amino groups are stable during reduction of the carbonyl group by one or more of the above procedures. The Clem-mensen reduction of keto acids is treated in method 269. 

Dialdehydes result when cyclic olefins are ozonized. Improved directions for the ozonolysis of unsaturated esters in glacial acetic acid to yield aldehyde esters have been given. The same procedure is applied to the preparation of aliphatic aldehydes containing halo, hydroxyl, and ether groups. ... 

Willgetodt reactions have been carried out on aromatic compounds containing halo hydroxyl, alkoxyl, amino," ... 

Side reactions which may occur during their formation have been studied. On the other hand, Schiff bases from substituted benzaldehydes and amines, aliphatic and aromatic, are more stable and have been prepared in large numbers. The benzaldehyde entity may carry a halo, hydroxyl, methoxyl, dialkylamino, or nitro group. Usually, an immediate reaction occurs upon mixing the two reactants either without a solvent or in dilute alcohol, as illustrated by the synthesis of benzalaniline, C,H,CH=NC,H, (87%). ... 

Several other functional groups may be present on the aromatic nucleus during the sulfonation reaction, including halo, hydroxyl, phen-oxyl, carboxyl, and amino " groups. Sulfonations of aniline and of dimethylaniline take place by different mechanisms. ... 

Substituted benzaldehydes and malonic acid give cinnamic acids in excellent yields. Among the common nuclear substituents are methyl, halo, " hydroxyl, methoxyl, " cyano, nitro, and diethylamino groups. Other /fi-arylacrylic acids have been made by the use of a-naphthaldehyde, phenanthraldehydes, and furfural. Phenyl-substituted aliphatic aldehydes have also been used in this condensation. ... 

Excellent directions are given for the preparation of p-tolylcarbinol (72%). The aryl radical may contain alkyl, halo, hydroxyl, methoxyl, and nitro groups. ... 

Imino esters containing halo/ hydroxyl/ carbalkoxyl/ and cyano groups have been prepared. 

Unsymmetrical secondary amines are readily prepared in good yields by the catalytic reduction of Schiff bases at moderate temperatures in high-or low-pressure equipment. Many examples have been cited. The intermediate imines are prepared from primary amines and aldehydes—very seldom from ketones—and may be used without isolation (cf. method 431). For the preparation of aliphatic amines, e.g., ethyl-w-propylamine and n-butylisoamylamine, a prereduced platinum oxide catalyst is preferred with alcohol as the solvent. Schiff bases from the condensation of aromatic aldehydes with either aromatic or aliphatic amines are more readily prepared and are reduced over a nickel catalyst. In this manner, a large number of N-alkylbenzylamines having halo, hydroxyl, or methoxyl groups on the nucleus have been made. Reductions by means of sodium and alcohol and lithium aluminum hydride have also been described,... 

Benzoic acids substituted with alkyl, halo, hydroxyl, alkoxyl, cyano, or nitro groups react to give the corresponding substituted anilines in 41-80% yields. The carboxyl group in an a-amino acid does not react with hydrazoic acid the reaction proceeds, however, if the amino group is further removed. This difference in reactivity is shown by the conversion of a-aminoadipic acid to i(-ornithlne (75%). ... 

Branched chain carbohydrate (Section 25 12) Carbohydrate in which the main carbon chain bears a carbon substituent in place of a hydrogen or hydroxyl group Bromohydrin (Section 6 17) A halohydnn in which the halo gen IS bromine (see halohydnn)... 

The labile hydroxyl group is easily replaced by treatment with thionyl chloride, phosphorous chlorides, or even aqueous hydrogen haUdes. At low temperatures aqueous hydrochloric (186) or hydrobromic (187) acids give good yields of 3-halo-3-methyl-l-butynes. At higher temperatures these rearrange, first to l-halo-3-methyl-1,2-butadienes, then to the corresponding 1,3-butadienes (188,189). 

Pyridazine N-ethoxycarbonylimide photolysis, 3, 13 Pyridazine, 4-gJycosyloxy-rearrangement, 3, 15 Pyridazine, halo-applications, 3, 56 Pyridazine, hexahydro-, 3, 40 photoelectron spectra, 2, 20-21 Pyridazine, hydrazino-reductive cleavage, 3, 34 synthesis, 3, 35 Pyridazine, hydroxy-acidity, 3, 4 Pyridazine, 3-hydroxyl-oxide... 

Direct halogenation of a 20-ketopregnane (lacking an hydroxyl at C-17) generally does not give satisfactory yields of the 21-bromo derivative, unless the presence of a C-16 substituent e.g., methoxyl or methyl) inhibits formation of the usual 17-bromo primary product. However, an indirect method has been devised. If the 20-ketaI is first prepared, it can be brominated satisfactorily at C-21 using trimethylphenylammonium tribromide as halo-... 

Non-hindered secondary hydroxyl groups have been shown, however, to react under the same conditions giving the corresponding halo derivatives. These direct replacements of hydroxyl groups by halogens are... 

Displacement of halogen by hydroxyl is a widely distributed reaction in the degradation of halo-alkanes and haloalkanoates. Although an apparently simple pathway involving two displacement... 

Verheyden, J.P.H. and Moffatt, J.G., Halo sugar nucleosides. I. Iodination of the primary hydroxyl groups of nucleosides with methyltriphenoxyphospho-nium iodide, /. Org. Chem., 35, 2319, 1970. 

Quinolines carrying 2- or 4-halo snbstitnents undergo nucleophilic substitution readily, in the same manner as 2- and 4-halopyridines. Hydroxyqninolines with the hydroxyl at positions 2 or 4 exist mainly in the carbonyl form, i.e. 2-quinolone and 4-qninolone. 

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