Hydrolysis reductive

Reductive hydrolysis of anilines, which may occur as an unwanted side reaction when anilines are reduced in aqueous media, can be turned to synthetic advantage. Reductive cleavage is facilitated by substitution on the nitrogen and by acidic media. Palladium is the preferred catalyst (33), Reductive hydrolysis of substituted anilines carrying chiral N-substituents gives chiral cyclohexanones (34), 

In a useful variant of the classical methylation procedure for linkage analysis in the structural determination of oligo- and poly-sacccharides, the fully methylated oligomer is treated with triethylsilane and boron trifluoride etherate or triethylsilane and trimethylsilyl trifluoromethanesulfonate. This procedure produces partially methylated anhydroalditols. These are acetylated and analyzed by GLC-MS.222 223 This reductive-cleavage method makes possible simultaneous determination of identity, ratio, linkage position, and especially the ring size for each monosaccharide component. 

---

A number of new j8-substituted alanines have been prepared from unsaturated azlactones by the usual reduction-hydrolysis procedures. An interesting example is the synthesis of DL-jS-ferrocenylalanine (33). ... 

Nitriles and oximes are considered together because of common features. Both functions are reduced to primary amines, both undergo coupling reactions to secondary amines, and both are subject to reductive hydrolysis. These similarities arise from a common intermediate, an imine. The imine is... 

In aqueous media, the intermediate imine can undergo a reductive hydrolysis. 

Ethyl p-dimcthylaminophenylacetate has been previously prepared in this laboratory by Fischer esterification of p-di-methylaminophenylacetic acid, the acid in turn being prepared by the reductive hydrolysis of -dimethylaminomandelonitrile.3... 

Negishi reaction 157 Nitriles, reduction/hydrolysis 25 Nitrogen heterocycles, on-resin cyclization, minopropenones 108 C-Nucleoside analogues 274... 

The number of chemical reactions used in CVD is considerable and include thermal decomposition (pyrolysis), reduction, hydrolysis, disproportionation, oxidation, carburization, and nitrida-tion. They can be used either singly or in combination (see Ch. 3 and 4). These reactions can be activated by several methods which are reviewed in Ch. 5. The most important are as follows ... 

Nitroalkenes are good dienophiles and the variety of transformations available for nitro groups makes them versatile intermediates.65 Nitro groups can be converted to carbonyl groups by reductive hydrolysis, so nitroethylene can be used as a ketene equivalent.66... 

Almost all the specific chemical reactions in biodegradation can be classified as oxidation-reduction, hydrolysis, or conjugation. Hydrolysis and oxidation-reduction have been discussed before. Conjugation involves the addition of functional groups or a hydrocarbon moiety to an organic... 

Penetrating through the respiratory and intestinal tracts, and the integument, pesticides undergo a dual transformation [6] both chemical transformations (oxidation, reduction, hydrolysis), and the formation of complex compounds with biochemical components in the body. 

One of the major uses of ADC compounds as dienophiles is the conversion of the Diels-Alder adducts into cyclic azoalkanes by a sequence of reduction, hydrolysis, decarboxylation, and oxidation reactions as shown in Eq. 

Diastereoselective intermolecular nitrile oxide—olefin cycloaddition has been used in an enantioselective synthesis of the C(7)-C(24) segment 433 of the 24-membered natural lactone, macrolactin A 434 (471, 472). Two (carbonyl)iron moieties are instrumental for the stereoselective preparation of the C(8)-C(ii) E,Z-diene and the C(i5) and C(24) sp3 stereocenters. Also it is important to note that the (carbonyl)iron complexation serves to protect the C(8)-C(ii) and C(i6)-C(i9) diene groups during the reductive hydrolysis of an isoxazoline ring. 

Monosaccharide residues containing vicinal hydroxyl groups are oxidized by periodate, and are subsequently removed in the reduction-hydrolysis step. Therefore, the positions to which such monosaccharide residues are linked can be located by methylation analysis performed before, and after, Smith degradation. Alternatively,59 the oxidized and reduced sample is methylated, the ether hydrolyzed, and the product realkylated with CD3I or CH3CH2I. This kind of procedure can have advantages over that first described. For example, methylation before the hydrolysis step hinders the acetal protection of hydroxyl groups that can occur in acid hydrolysis.7... 

Detoxification pathways (oxidation/reduction/hydrolysis/conjugation) Toxification pathways (oxidation/reduction/hydrolysis/conjugation)... 

All three chlorine atoms of chloroform take part in the Friedel-Crafts reaction the product of the reaction with benzene is the important hydrocarbon triphenylmethane, the parent substance of the well-known class of dyes. Paraleucaniline, [(p) NH2.C6H4]3CH, has been converted into triphenylmethane by reductive hydrolysis of its tris-diazo-com-pound (E. and 0. Fischer). 

Since ketone R)-16 was prepared in a non-selective way when an achiral imino enolate was alkylated, it was considered whether alkylation of chiral enolates, such as that of oxazoline 18, with benzyl bromide 14, would provide stereoselective access to the corresponding alkylation product 19 with R-configuration at C(8) (Scheme 4). Indeed, alkylation of 18 with 14 gave the biaryl 19 and its diastereoisomer almost quantitatively, in a 14 1 ratio. However, reductive hydrolysis using the sequence 1. MeOTf, 2. NaBH4, and 3. H30", afforded hydroxy aldehyde 20 in 25% yield at best. Furthermore, partial epimerization at C(8) occurred (dr 7.7 1). An alternative route, using chiral hydrazones, was even less successful. 

Another derivatization approach is reduction of the hydroperoxide, followed by structural characterization of the corresponding alcohol, which is usually easier to handle. Thus, the structure of amino acid hydroperoxides can be characterized more easily if, after having ascertained the hydroperoxide nature of the compound, it is reduced to the alcohol with NaBH4. The structure of three valine hydroperoxides obtained on y-radiation of bovine serum albumin, a tripeptide (31) or valine (34) was elucidated after reduction, hydrolysis (if necessary), chromatographic separation, and application of the usual MS and NMR methods on the individual hydroxy derivatives of valine. ... 

---