Benzaldehyde oxime ether

Treatment of benzaldehyde oxime ether (166) with butyllithium (pentane/-10 C) demonstrates the complexity of the reaction (Scheme 32) as the desired alkoxyamine (167 R = Bu) is accompanied by other oxime-derived side products" (entry 1, Table 12). Selectivity is reagent/solvent dependent as allyl Grignard (ether)," allylzinc bromide (THF)," and butyllithium (THF)" treatment produce predominantly amine (171 R = allyl) (the Beckmann rearrangement derived product), alkoxyamine (167 R = allyl) (the oxime addition product) and ketone (169 R = Bu) (the nitrile-derived pro ct), respectively (entries 2-4, Table 12). 

Reaction of the enantiomerically pure alkoxyamines 3, prepared from L-ephedrine or norephedrine derivatives 1 with acetaldehyde, isobutyraldehyde or benzaldehyde using ethanol as the solvent, afford the corresponding oxime ethers 4 as mixtures of E/Z-stereoisomers11. 

Tandem processes mediated by triethylborane involving conjugate addition to enones followed by aldol reaction are reported (Scheme 52, Eq. 52a). More recently, a tandem process involving addition of an isopropyl radical to an o ,/3-unsaturated oxime ether afforded an azaenolate intermediate that reacts with benzaldehyde in the presence of trimethylaluminum. The aldol product cyclizes to afford an isopropyl substituted y-bulyroloaclonc in 61% overall yield (Scheme 52) [116]. In these reactions, triethylborane is acting as a chain transfer reagent that delivers a boron enolate or azaenolate necessary for the aldolization process. 

Formation of N—O bonds via amination with oxaziridines has been little studied. Benzaldehyde oxime 0-ethyl ether, along with other products, are obtained on treatment of 3-phenyloxaziridine (56 Me = H) with sodium ethoxide (67LA131,91S327). 

Reaction of dimethyl l,2,4,5-tetrazine-3,6-dicarboxylate with the oxime ether of 4-(dimethyl-amino)benzaldehyde affords dimethyl 5-[4-(dimethylamino)phenyl]-l,2,4-triazine-3,6-dicarb-oxylate (10).342... 

Aminobenzoic acid [(2-hydroxyphenyl) methylenejhydrazide, A-00110 2-Hydroxybenzaldehyde A -(4-aminobenzoyl) hydrazone, H-00103 2-Hydroxybenzaldehyde 6-methyl-2-nicotinoylhydrazone, H-00106 2-Hydroxy nzoic acid [2-(2-pyridinyl) ethylidenejhydrazide, H-00121 2-(4-Hydroxyphenylazo)benzaldehyde Me ether, oxime, in H-00448 2,2 -Iminobisbenzamide, in 1-00013 2-Methyl-4-pyridinecarboxylic acid [(2-hydroxypheny 1) methylene] hydrazide, M-00272... 

In a 250 ml. conical flask mix a solution of 14 g. of sodium hydroxide in 40 ml. of water and 21 g. (20 ml.) of pure benzaldehyde (Section IV,115). Add 15 g. of hydroxylamine hydrochloride in small portions, and shake the mixture continually (mechanical stirring may be employed with advantage). Some heat is developed and the benzaldehyde eventually disappears. Upon coohiig, a crystalline mass of the sodium derivative separates out. Add sufficient water to form a clear solution, and pass carbon dioxide into the solution until saturated. A colourless emulsion of the a or syn-aldoxime separates. Extract the oxime with ether, dry the extract over anhydrous magnesium or sodium sulphate, and remove the ether on a water bath. Distil the residue under diminished pressure (Fig. 11,20, 1). Collect the pure syn-benzaldoxime (a-benzald-oxime) at 122-124°/12 mm. this gradually solidifies on cooling in ice and melts at 35°. The yield is 12 g. 

The Ponzio reaction provides a useful route to gem-dinitro compounds and involves treating oximes with a solution of nitrogen dioxide or its dimer in diethyl ether or a chlorinated solvent. The Ponzio reaction works best for aromatic oximes where the synthesis of many substituted aryldinitromethanes have been reported. Compound (56), an isomer of TNT, is formed from the reaction of dinitrogen tetroxide with the oxime of benzaldehyde (55) followed by mononitration of the aromatic ring with mixed acid. Yields are usually much lower for aliphatic aldoximes and ketoximes. " The parent carbonyl compound of the oxime is usually the major by-product in these reactions. 

Benzaldehyd 3.5-Dimethyl-2,4,6-tricyan- -oxim X/4, 52 Ether Bis-[4-diazonio-phenyl]-(bis-tetrafluoroborat) VI/lc, 259... 

Secondary amines reacted to form hydrazines in yields of 90% and better. Aniline can be converted to phenylhydrazine. Sometimes the addition was followed by the elimination of water rather than the aminated nucleophile. For example, treatment of 3,3-pentamethyleneoxaziridine with methoxide ion produced cyclohexanone oxime (9-methyl ether. Formanilide reacted with 3-phenyloxaziridine in the presence of sodium ethoxide to produce benzaldehyde phenyUiydrazone. " Of considerable interest is the reaction of Schiff bases with these oxaziridines to produce diaziridines. Other examples are given in Schmitz recent review. One intramolecular version of this kind of amination is known oxaziridine 57 was converted to benzophenone and 5,6-dihydro-4H-l, 2-thiazine 58 upon heating. ... 

Further aminations are the formation of cyclohexanone oxime 0-methyl-ether from 34 and methanol, and of benzaldehyde phenylhydrazone from 3-phenyloxaziridine 41 and formanilide. ... 

---