Amines aldoximes

Selenols are capable of acting as useful reducing agents. Thus, benzeneselenol (PhSeH) reduces imines to amines, aldoximes to hydroxylamines, and selectively reduces the C=C double bond in conjugated enones the last two transformations are photochemically induced. Similarly, hydrogen selenide (H3Se) photoreduces ketones and aldehydes to alcohols. ... 

Internal nitroalkenes can be reduced to the corresponding ketox-imes by SnCla. The second method is a modification of the first, also allowing terminal nitroalkenes (such as nitrostyrenes) to be reduced to aldoximes. The oximes, in turn, can either be reduced to the corresponding amines, or cleaved to form the carbonyl compound. 

A variety of bifunctional compounds react with the bismaleimides to form polymers by rearrangement reactions. These include amines, sulphides and aldoximes (Figure 18.41). 

The addition of (E)- and (Z)-crotylboronates 7 to aldoximes 6 has been realized in good yield by performing the reaction under 3-6 x 10° Torr pressure10. The resulting hydroxylamines 8 can easily be reduced to yield the primary amines. The addition of E-l leads preferentially to the anh-diastereomcr 8, while (Z)-crotylboronate 7 shows a modest selectivity towards formation of the vyy -diastereomer 8 (same sense as in the reaction with aldehydes). Some effort has been made to elucidate the mechanism, but this is not yet well understood. 

Both aldoximes and ketoximes can be reduced to primary amines with LiAlH4. The reaction is slower than with ketones, so that, for example, PhCOCH=NOH gave 34% PhCHOHCH=NOH. Among other reducing agents that give this reduc-... 

Interesting examples of the addition of N-nucleophiles to nitrile oxides are syntheses of chelated Z-amidoxime, N-[2-(dimethylaminomethyl)phenyl]mesitylene-carboamidoxime (118), and pyranosyl amidoximes (119) from the respective nitrile oxides and amines. Aromatic aldoximes undergo unusual reactions with chloramine-T (4 equiv, in refluxing MeOH). N-(p-toly 1 )-N-(p-tosy 1 )benzamides are formed via addition of 2 equiv of chloramine-T to the intermediate nitrile oxide followed by elimination of sulfur dioxide (120). 

Similarly the reduction of both aldoxime and ketoxime gives again primary amines. 

Aldoximes yielded primary amines by catalytic hydrogenation benzaldehyde gave benzylamine in 77% yield over nickel at 100° and 100 atm [803, with lithium aluminum hydride (yields 47-79%) [809, with sodium in refluxing ethanol (yields 60-73%) [810] and with other reagents. Hydrazones of aldehydes are intermediates in the Wolff-Kizhner reduction of the aldehyde group to a methyl group (p. 97) but are hardly ever reduced to amines. 

The use of soluble amine bases failed to give products, whereas the heterogeneous conditions KOH/THF proved optimal in promoting aldoxime formation for a broad range of substrates. Optically active nitroalkanes including aromatic (both electron-rich and electron-deficient), heteroaromatic, branched and unbranched aliphatic substrates, as well as substrates that incorporate unprotected alcohol functionalities were successfully reduced. 

Reduction of ketoximes.1 Ketoximes are reduced by LiAlH4 to a mixture of primary and secondary amines. In contrast, reduction with LiAlH4-HMPT in the molar ratio 1 10 in refluxing THF (130°, 3 hours) results in ketones. HMPT is believed to prevent further reduction of the imine intermediate and to facilitate hydrolysis. This method is not useful for reversion of aldoximes to aldehydes because of dehydration to nitriles. 

The methods used for preparing cyanobenzo[6]thiophenes are merely summarized in the present section they are discussed in more detail elsewhere in this review. Cyanobenzo[6]thiophenes are most conveniently prepared by heating a halobenzo[6]thiophene with cuprous cyanide in a suitable solvent (Section VI, D, 2), or by means of a Sandmeyer reaction of the appropriate diazotized amine (Section VI, F, 4 and 5). Less commonly they are prepared from aldehydes or aldoximes, by methods described in Section VI, L, 1, or from carbox-... 

The acid-catalyzed conversion of ketoximes and aldoximes to amides or amines (the amide is often hydrolyzed to the corresponding amine under the reaction conditions) is known as the Beckmann rearrangement after its discoverer.147 The reaction and its widely accepted mechanism are shown in Equation 6.54. 

Aldoximes are reduced to amines by hydrogen at 180—220° in the presence of reduced nickel or copper with benzaldoxime, however, the chief product is benzaldehyde when copper is used, and toluene when nickel is used.13... 

Isopropylamine is formed in the reduction of aeetoxime in sulphuric-acid solution at a lead cathode (Tafcl and Pfeffer-mann1). This process is a general one. The electrolytic reduction of ketoximes leads, like that of the aldoximes and phenylhydrazones, to the final formation of amines. About 66% of the theoretically possible quantity of isopropylamine is formed from aeetoxime acetonphenylhydrazone gives about the same yield. 

Reeve and Christian compared Raney Ni and Raney Co (W-7 type) for the hydrogenation of six aliphatic and aromatic aldoximes and ketoximes in the presence or absence of ammonia.26 From the results summarized in Table 8.1, it is notable that Raney Co gives high yields of primary amine in ethanol or dioxane without addition of ammonia as seen in the results with butyraldoxime, 2-butanone oxime, and acetophenone oxime. On the other hand, Raney Ni usually requires an ammoniacal solvent for best results, with the exception of acetophenone oxime, which gave high yields of primary amine in the absence of ammonia. 

A number of investigations on the synergistic effect of a second extractant, such as amines and oximes, on the extraction of metal carboxylates have been carried out. The utilized synergists include 8-hydroxyquinoline-2-aldoxime for Zr(IV) and Hf(IV) (122,123), various amines (25), Lix 63 (27) and nonylphenol (28) for Cu(II), dialkylphos-phoric acids for Hf(IV) (44), rhodamine B for Be(IE) (102), trioctylphos-phine oxide for U(VI) (69, 77), p-alkylphenol for Cs(I) (1), collidine for Zr(IV) and Sc(IEI) (62), and nonchelating oximes for Ni(II) and Co(II) (103). Mareva et al. (77) have successfully utilized a salicylic acid-trioctylphosphine oxide mixture for the separation of uranium from rare earths, thorium, zirconium, and iron. 

Triethoxydiiodophosphorane, (C2HsO)3Pl2 (1). Mol. wt. 389.0. The reaction of triethyl phosphite with iodine in CHjCN, CH2CI2, or ether at 0° results in a complex formulated as 1. Substances of this type are intermediates in the Arbuzov reaction. The phosphorane is stable in solution for several days. In combination with 1 equiv. of triethylamine it can dehydrate amides and aldoximes to nitriles. It effects condensation of acids and amines to amides. The paper cites one example of use for... 

---