Hydrogenation oximes

Compounds containing one or more —OH or —SH groups, such as water, alcohols, phenols, oximes, hydrogen sulphide and thiols. 

CN ( )-5-methoxy-1 -[4-(trifluoromethyl)phenyl]-1 -pentanone 0-(2-aminoethyl)oxime hydrogen maleate... 

See Ethyl 2-formylpropionate oxime Hydrogen chloride Sulfuric acid Cyclopentanone oxime See other CATALYTIC IMPURITY INCIDENTS, OXIMES... 

Asymmetric catalytic reduction reactions represent one of the most efficient and convenient methods to prepare a wide range of enantiomerically pure compounds (i.e. a-amino acids can be prepared from a-enamides, alcohols from ketones and amines from oximes or imines). The chirality transfer can be accomplished by different types of chiral catalysts metallic catalysts are very efficient for the hydrogenation of olefins, some ketones and oximes, while nonmetallic catalysts provide a complementary method for ketone and oxime hydrogenation. 

OXIMES Hydrogen peroxide. Pyridinium chlorochromate-Hydrogen peroxide. Sodium dithionite. Vanadium(II) chloride. 

Reduction of saturated l-oximino-5a-steroids with usual reagents gives the la-amino-derivatives. The previously unknown 1/3-amino-compounds have now been obtained by reduction of the A2-unsaturated 1-oxime. Hydrogenation (Pt-H2) leads to the saturated la- and 1/3-amines directly, while zinc-acetic acid gave the unsaturated amines which could be hydrogenated in a separate step to give the saturated amines.197 The four isomeric 16-azido-17-alcohols, and thence the 16-amino-17-alcohols, have been prepared by the routes indicated in Scheme 8 [3-methoxyoestra-l,3,5(10)-triene series]. The 16/3,17/3-epoxide gave a mixture of two tra/ts-azido-alcohols.198... 

In reactions in solvent, the oxime acts both as a reaction partner and as a base. The oxime-hydrogen chloride-adduct can be isolated as a separate liquid phase. By reacting with... 

Figure 3. Two structural representations of the calculated geometry of anti-J-methyl-2-pyridiniumcarbaldoxime cation (V) in its most stable form. The second structure is a perpendicular view to the first one to depict the oxime geometry better. The oxime group is 80° out of the plane of the ring. The oxime hydrogen is trans and essentially planar with respect to the oxime. The methyl group hydrogens are rotated 20, 140, 260° respectively relative to the pyridine ring, thus occupying the least hindered position from the oxime.

Figure 8. Calculated geometry of the most stable form of axiti-l-methyl-1,6-dihydropyridine-2-carbaldoxime (XVI). The oxime group is rotated 86° from the plane of the ring and the oxime hydrogen is trans and planar with the oxime function. The methyl hydrogens are rotated 25,145, and 265° with respect to the ring. The ring is essentially planar.

An example, again showing the applicability of the oxime hydrogenation for the stereoselective preparation of amines is ... 

Examples of steroid oximes hydrogenated in a similar manner are given in Table 5. 

The four adamantane derivatives, 2-hydroxyadamantane, 2-adamantanone, 2-adamantanone oxime and 2-adamantanecarboxylic acid (Formula 5.4) all have a nearly spherical shape. Screening experiments were performed with each possible pair of the four compounds, but only two co-crystals were found hydroxyadamantane- adamantanone and adamantanone oxime-adamantane-carboxylic acid. The alcohol-ketone and acid-oxime hydrogen bonds provide strong supramolecular synthons for the formation of these co-crystals, while for the other combinations possible heteromolecular synthons are not preferred to homomolecular ones. The results thus show that shape similarity cannot overcome the effect of good homomolecular synthons. 

To inhibit binding of a second copper atom and to prevent possible hydrogen atom transfer reactions, the bridging oxime hydrogen was replaced with BF2 via treatment with Bp3-etherate in dioxane. The Cu(I) complex reacts with monodentrate (i.e., CO, 1-methylimidazole, acetonitrile) yielding five-coordinate adducts. Of course such a model is not an accurate mimic of the active sites of any copper protein but suggests that consideration of Cu(I) active site structures must include the possibility of five-coordination. 

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