Oxime derivatives preparation

A number of oxime derivatives of rifaldehyde have been prepared. Many of these derivatives exhibit good activity against rifampicin-resistant organisms (151,152). 

Note that the acetonitrile oxide cyclooligomers (e.g. 13) are not true oxime derivatives. Such derivatives have been prepared from biacetyl, however . Derivatives related to 14, below, were prepared and found not to be good complexing agents. They were, nevertheless, capable of phase transferring either sodium or potassium permanganate into dichloromethane. 

The reduction of oxime derivatives (section IV-C) is useful for the preparation of steroidal amines labeled with a deuterium on the nitrogen-bearing carbon atom... 

Preparation and use of amphiphilic oximes, derivatives of pyridine, pyridazine, pyrimidine, and pyrazine 98CFY469. 

Hydrazones are also useful substrates in the preparation of pyrazoles. Reaction of N-monosubstituted hydrazones with nitroolefins led to a regioselective synthesis of substituted pyrazoles <060L3505>. lf/-3-Ferrocenyl-l-phenylpyrazole-4-carboxaldehyde was achieved by condensation of acetylferrocene with phenylhydrazine followed by intramolecular cyclization of the hydrazone obtained under Vilsmeier-Haack conditions <06SL2581>. A one-pot synthesis of oxime derivatives of l-phenyl-3-arylpyrazole-4-carboxaldehydes has been accomplished by the Vilsmeier-Haack reaction of acetophenone phenylhydrazones <06SC3479>. 

This protocol could be extended to a range of different ,/i-unsaturated carbonyl compounds and either activated or deactivated aryl iodides [22], An application of related Heck chemistry to the synthesis of methylated resveratrol (3,4, 5-trihydroxy-( )-stilbene) is shown in Scheme 6.4 [23]. The phytoalexin resveratrol exhibits a variety of interesting biological and therapeutic properties, among them activity against several human cancer cell lines. Botella and Najera have shown that the trimethyl ether of resveratrol (Scheme 6.4) can be rapidly prepared by microwave-assisted Heck reaction of the appropriate aryl iodide and styrene derivatives, using the same oxime-derived palladacycle as indicated in Scheme 6.3. 

If the addition of hydrogen takes place in a 1,2-mode the products are oximes, hydroxylamines, amines, and carbonyl compounds resulting from the hydrolysis of the oximes [567], Oximes and carbonyl compounds also result from reductions of a,/3-unsaturated compounds with iron [569, 570] and an oxime was prepared by catalytic hydrogenation of a )S-nitrostyrene derivative over palladium in pyridine (yield 89%) [571]. 

Effective synthesis of spiroisoxazoline derivatives was elaborated using hypervalent iodine reagents. Thus, treatment of o-phenolic oximes 217 with phenyliodonium diacetate (PIDA) in MeCN at 0°C afforded spiroisoxazoUnes 218 in moderate yields (equation 94) . Oximes 219, prepared in situ from 2-trifluoromethylchromones, in the acidic media also led to spiroisoxazoUnes 220 (equation 95) . ... 

Reaction of aldoximes with dimedone derivatives under microwave irradiation leads to partially hydrated acridine derivatives . Eused heterocyclic compounds containing partially hydrogenated pyridine and quinoUne rings were prepared by intramolecular cycloaddition reaction of 5-alkynyl oxime derivatives . (Z)-l,10a-Dihydropyrrolo[l,2-i>]... 

Methoxypyrazine-2-one Af-oxides 341 were prepared from oxime derivatives 340 by one-pot cyclization in the presence of DCC/DME with subsequent interaction with Me2S04/K2C03 and NaOH (equation 148) . Similar intramolecular cyclizatiou of ester and oxime O-ethers groups iu the presence of lithium arylthiolate also leads to pyrazin-2-one ring formation . ... 

In later work, Mioskowski and co-workers (320) used cyclohexenone 160 to prepare oxime 161 as part of a twofold nitrile oxide strategy to synthesize the basic taxol ring system. Cycloaddition of 161 was effected by means of sodium hypochlorite and gave tricyclic isoxazoline 162, which feamres rings A and C of taxol (320) (Scheme 6.79). Nagaoka and co-worker tried to apply a related intramolecular cycloaddition toward the synthesis of the taxane A/B ring but this approach failed, producing only the oxime derivative (248) (see Scheme 6.44, Section 6.3.1). 

Photopolymerizable naphthyl oxime ester, (II), derivatives prepared by Kunimoto et al. (2) were effective in the radiation range of from 150 to 600 nm or with an electron beam or X rays. 

Research Focus Preparation of p-terphenyl-based oxime derivatives for use as latent acids activated by irradiation with actinic electromagnetic radiation and electron... 

Additional p-terphenyl halogenated oxime latent acids, (III), were prepared by this group (1) in an earlier investigation and had an E0 of 1.51mJ/cm2. Tetrahalogenated oxime derivatives, (IV), were also prepared by this group... 

A potential method for the preparation of novel amino acids via the highly selective addition of radicals to the glyoxylic oxime derivative of Oppolzer s camphor sultam (88) has been reported.181 Both Lewis acid and non-Lewis acid-mediated reaction conditions for the addition of alkyl radicals generated from alkyl iodides and Et3B/Bu3SnH were examined. A new chiral auxiliary based upon (R,R)-2,5-diphenylpyiTolidine has been used in the addition of phenylthiyl radicals to unsaturated methacrylamides. The selectivity was found to be better than that reported for the structurally related 2,5-dimethylpyrrolidine derivative.182... 

Oxime derivatives were prepared by Kunimoto [1] containing both esteroxime and aryl ketone components, (I), were particularly effective in photopolymerization reactions. 

The Beckmann rearrangement is one of the typical reactions of oxime derivatives and the N-substituted nitrilium ion intermediates have been widely exploited as synthetic intermediates for the preparation of nitrogen-containing heterocycles, " while few examples have been reported for the nucleophilic substitution on the sp nitrogen atom of oximes. Even though, in some of them, carbon-nitrogen bond formation is realized, these reactions have not been well generalized as synthetic tools. ... 

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