Ketoximes

Ketoximes are usually formed less readily than the aldoximes for their preparation the ketone is mixed with the necessary proportions of sodium acetate and hydroxylamine hydrochloride in aqueous or alcoholic solution, and the liquid heated on the water-bath during 1-2 hours, or the ketone, in alcoholic solution, may be heated in a sealed tube with the hydrochloride at i6o  

In many cases it is highly advantageous to allow the carbonyl derivative and the hydroxylamine to react in 

Zinc dihydroxylamine hydrochloridey ZnClg-aNKgOH, has been used chiefly for the preparation of ketoximes as its resolution into hydroxylamine and anhydrous zinc chloride facilitates the elimination of water. It is prepared by adding zinc oxide (i part) to hydroxylamine hydrochloride 

The formation of well-crystallized derivatives of semicarbazine has proved extremely useful in the investigation of terpene compounds which often yield liquid oximes, and phenylhydrazones that only crystallize with difficulty and readily undergo decomposition. As a rule the aldehyde or ketone combines with semi- 

Aliphatic ketones have varying velocities of interaction with different salts of semicarbazine, hence,by the 

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When treated with certain reagents, the ketoximes in particular undergo the Beckmann rearrangement to isomeric acid amides (p. 227). 

Place 80 g, of hydroxylamine sulphate (or 68-5 g. of the hydrochloride), 25 g. of hydrated sodium acetate, and 100 ml. of water in a 500 ml. flask fitted with a stirrer and a reflux water-condenser, and heat the stirred solution to 55-60°. Run in 35 g (42 nil,) of -hexyl methyl ketone, and continue the heating and vigorous stirring for ij hours. (The mixture can conveniently be set aside overnight after this stage.) Extract the oily oxime from the cold mixture twice with ether. Wash the united ethereal extract once with a small quantity of water, and dry it with sodium sulphate. Then distil off the ether from the filtered extract, preferably using a distillation flask of type shown in Fig. 41 (p. 65) and of ca, 50 ml, capacity, the extract being run in as fast as the ether distils, and then fractionally distil the oxime at water-pump pressure. Collect the liquid ketoxime, b.p. 110-111713 mm. Yield, 30-32 g. 

Methyl n-hexyl ketoxime. From methyl n hexyl ketone (Section 111,71) ill 90 per cent, yield. B.p. 106-108°/12 mm. 

Cycloahphatic amine synthesis routes may be described as distinct synthetic methods, though practice often combines, or hybridi2es, the steps that occur amination of cycloalkanols, reductive amination of cycHc ketones, ring reduction of cycloalkenylarnines, nitrile addition to ahcycHc carbocations, reduction of cyanocycloalkanes to aminomethylcycloalkanes, and reduction of nitrocycloalkanes or cycHc ketoximes. 

Vinyl Pyrroles. Relatively new synthetic routes based on a one-pot reaction between ketoximes and acetjiene ia an alkaU metal hydroxide—dimethyl sulfoxide (DMSO) system have made vinyl pyrroles accessible. It requires no pyrrole precursors and uses cheap and readily available ketones (42). 

Vinyl chloride reacts with sulfides, thiols, alcohols, and oximes in basic media. Reaction with hydrated sodium sulfide [1313-82-2] in a mixture of dimethyl sulfoxide [67-68-5] (DMSO) and potassium hydroxide [1310-58-3], KOH, yields divinyl sulfide [627-51-0] and sulfur-containing heterocycles (27). Various vinyl sulfides can be obtained by reacting vinyl chloride with thiols in the presence of base (28). Vinyl ethers are produced in similar fashion, from the reaction of vinyl chloride with alcohols in the presence of a strong base (29,30). A variety of pyrroles and indoles have also been prepared by reacting vinyl chloride with different ketoximes or oximes in a mixture of DMSO and KOH (31). 

Although 1,2-benzisothiazoles can be prepared by the oxidation method, they are also available by cyclization of o-mercaptobenzaldoximes and ketoximes with polyphosphoric acid (72AHC 14)43, 73JCS(P1)356, 77JCS(P2)1114). This method has been improved by the use of S-t- butyl analogues, which do not suffer from the instability of the free thiols (79SST 5)345). 

One of the more important approaches to 1-azirines involves a similar base-induced cycloelimination reaction of a suitably functionalized ketone derivative (route c. Scheme 1). This reaction is analogous to route (b) (Scheme 1) used for the synthesis of aziridines wherein displacement of the leaving group at nitrogen is initiated by a -carbanionic center. An example of this cycloelimination involves the Neber rearrangement of oxime tosylate esters (357 X = OTs) to 1-azirines and subsequently to a-aminoketones (358) (71AHC-(13)45). The reaction has been demonstrated to be configurationally indiscriminate both syn and anti ketoxime tosylate esters afforded the same product mixture of a-aminoketones... 

SONN MULLER Aldehyde synthesis Aldehyde synthesis from amides or ketoximes, by reduction of irmno chiondes. 

Phenyl 2-pyridyl ketoxime [1826-28-4] M 198.2, m 151-152 . Crystd from EtOH (charcoal). 

The treatment of ketoximes with lithium aluminum hydride is usually a facile method for the conversion of ketones into primary amines, although in certain cases secondary amine side products are also obtained. Application of this reaction to steroidal ketoximes, by using lithium aluminum deuteride and anhydrous ether as solvent, leads to epimeric mixtures of monodeuterated primary amines the ratio of the epimers depends on the position of the oxime function. An illustrative example is the preparation of the 3(x-dj- and 3j5-di-aminoandrostane epimers (113 and 114, R = H) in isotopic purities equal to that of the reagent. 

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