Conversion to oximes

The reduction of an aliphatic nitro compound containing an a-hydrogen (R R CHN02) may be stopped at the stage of the oxime (R R C=NOH). Despite the great synthetic importance of these nitro compounds, their photochemical conversion to oximes has not... 

Indoles may as well serve as dienophilic compounds for hetero Diels-Alder reactions with nitrosoalkenes. However, the resulting adducts are not stable and undergo further conversion to oximes which represent useful intermediates for the straightforward synthesis of tryptophane derivatives [376,377]. 

N-methyl carbamates do not need activation to inhibit ChEs. However, at least in the case of aldicarb, inhibition increases with metabolism. Aldicarb is rapidly oxidized to the relatively stable aldicarb sulfoxide, which in turn is more slowly metabolized to aldicarb sulfone, a stronger AChE inhibitor. These products are then detoxified by conversion to oximes and nitriles, which in turn are degraded to aldehydes, acids, and alcohols. Procarbamate derivatives were... 

Fig. 17 Preparation of gem-dichloroalcanes from carbonyl compounds directly by reaction with PCI5 or more selective preparation via conversion to oximes with subsequent chlorination [14]...

Hydroxybenzaldehyde has extensive use as an intermediate in the synthesis of a variety of agricultural chemicals. Halogenation of Nhydroxybenzaldehyde, followed by conversion to the oxime, and subsequent dehydration results in the formation of 3,5-dihalo-4-hydroxybenzonitrile (2). Both the dibromo- and dhodo-compounds are commercially important contact herbicides, hromoxynil [1689-84-5] (2) where X = Br, and ioxynil [1689-83-4]( where X = I respectively (74). Several hydrazone derivatives have also been shown to be active herbicides (70). 

Nylon-12. Laurolactam [947-04-6] is the usual commercial monomer for nylon-12 [24937-16-4] manufacture. Its production begins with the mixture of cyclododecanol and cyclododecanone which is formed in the production of dodecanedioic acid starting from butadiene. The mixture is then converted quantitatively to cyclododecanone via dehydrogenation of the alcohol at 230—245°C and atmospheric pressure. The conversion to the lactam by the rearrangement of the oxime is similar to that for caprolactam manufacture. There are several other, less widely used commercial routes to laurolactam (171). 

Indirect conversion of oximes to nitro compounds viact-halo nitro compounds has provided a useful method for synthesis of nitro compounds, as shown m Scheme 2 1... 

Oximinoimidazolides can be obtained from oximes and CDI with retention of stereochemistry heating in octane or nonane under anhydrous conditions leads to their conversion to imidazolylimidates [123]... 

By 1990, most of the catalytic reactions of TS-1 had been discovered. The wide scope of these reactions is shown in Fig. 6.1.35 Conversions include olefins and diolefins to epoxides,6,7 12 16 19 21 24 34 36 38 13 aromatic compounds to phenols,7,9 19 25 27 36 ketones to oximes,11 20 34 46 primary alcohols to aldehydes and then to acids, secondary alcohols to ketones,34-36 42 47-30 and alkanes to secondary and tertiary alcohols and ketones.6 34 43 31 52... 

The conversion of oximes to nitroalkanes has been achieved by employing an Mo(IV) oxodiperoxo complex as oxidant in acetonitrile. Both aldoximes and ketoximes are converted into the corresponding nitroalkanes (Eqs. 2.61 and 2.62),123 representing a complementary synthetic route to the use of the UHP method. 

The one-pot conversions of oximes to gem-halonitro compounds have been achieved by using A(/V,/V.-trihalo-l,3,5-triazines,131 chloroperoxidase in the presence of hydrogen peroxide and potassium chloride,132 or commercial OXONE and sodium chloride.133 Of these methods, the case of OXONE may be the most convenient (Eq. 2.65). 

The conversion of oximes to nitro compounds have provided a useful method for the preparation of nitro sugars (see Eqs. 2.66-2.69)36,136 137 138... 

Table 4 Conversion of anomeric sugar aldehydes to oximes 302 and furoxans 304...

Benzophenone, conversion to ethyl /S-hydroxy-0,0-diphenylpro-pionate, 44, 57 Benzophenone oxime, 44, 52 Benzopyrazole, 42, 69 3-Benzoylpropionic add, condensation with benzaldehyde to give a-benzylidene-y-phenyl-A y -bu-tenolide, 43, 3 N-Benzylacetamide, 42,18 n-Benzyiacrylamide, 42,16 Benzyl alcohol, reaction with acrylonitrile, 42,16... 

Research has focused on improving the efficiency of the halogenation-oxidation-reduction route by using reagents that perform the halogenation-oxidation in one step. Hypochlorous acid-hypochlorite and hypobromous acid-hypobromite " systems have also been explored for the direct conversion of oximes to a-bromonitroalkanes and a-chloronitroalkanes respectively. Some A-haloheterocycles have been reported to affect direct oxime to a-halonitroalkane conversion, and on some occasions, the use of NBS or the free halogens also leads to a-halonitroalkanes. A mixture of oxone and sodium chloride as a suspension in chloroform is reported as a one-pot method for the direct conversion of oximes to a-chloronitroalkanes. ... 

Acetylenic oximes undergo in a similar manner conversion to 3,5-disubstituted isoxazoles. Thus, oximes 195 in the system K2C03/Me0H at room temperature afforded isoxazoles 196 in excellent yields (equation 85). a, S-Unsaturated ketoximes 197 can be also easily transformed to the corresponding 5-arylisoxazoles 198 (yield up to 95%) by treatment with iodine and potassium iodide. The presence of isoxazoline was detected in the reaction mixture (equation 86) . a, S-Unsaturated ketoximes in the presence of palladium catalyst afforded isoxazolines . 

Sorghum microsomal enzyme system Production of 25 from tyrosine, isomerization of oxime 25 to 26, and its conversion to hydroxymandelonitrile 106, 117... 

Sorghum cytochrome P450ryr(CYP79Al) Catalyzes conversion of tyrosine to oxime 25. For the reconstimted system, A m = 0.21 mM and turnover is 228 min 105... 

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