Aldehydes oximes from

Substances of this kind are called nitrones Their method of formation is quite analogous to that of the oximes from aldehydes and hydroxylamine. 

The second example was the pyruvate decarboxylase catalyzed formation of (ll )-l-hydroxy-l-phenyl-2-propanone (PAC) with benzaldehyde as substrate (Fig. 5 a) [64]. This second reaction shows one potential limitation of this method. Some compounds are too volatile for direct measurement by MALDl mass spectrometry or they do not ionize directly due to their nonpolar character. In this case, these compounds have to be derivatized prior to their measurement in order to reduce their volatihty and to introduce ionizable functions. This is, however, often very easy using well estabhshed quantitative reactions, e.g., formation of oximes from aldehydes and sugars (Fig. 5b). 

Oximes - Compounds of structure R2C=NOH derived from condensation of aldehydes or ketones with hydroxylamine. Oximes from aldehydes may be called aldoximes those from ketones may be called ketoximes. [5]... 

From aldehydes by conversion into the oximes, followed by removal of the elements of water by the action of acetic anhydride, for example ... 

Synthesis from Aldehydes and Ketones. Treatment of aldehydes and ketones with potassium cyanide and ammonium carbonate gives hydantoias ia a oae-pot procedure (Bucherer-Bergs reactioa) that proceeds through a complex mechanism (69). Some derivatives, like oximes, semicarbazones, thiosemicarbazones, and others, are also suitable startiag materials. The Bucherer-Bergs and Read hydantoia syntheses give epimeric products when appHed to cycloalkanones, which is of importance ia the stereoselective syathesis of amino acids (69,70). 

MILLER - SNYDER Aiyl Cyanide Synthesis Synthesis of benzonitnies from aldehydes via oxime ethers Formation of p-cyanophenol from p nrtrobenzaldoxime and p-nitiobenzonitnle (used as a sometimes recyclable chain carrier)... 

Most studies in this field have been on nitrones. One of the reasons for this is probably because nitrones are readily available compounds that can be obtained from aldehydes, amines, imines, and oximes [2, 11]. Moreover, most acyclic ni-... 

A small number of examples is available for the synthesis of E and Z isomers of oximes. In many cases, E isomers were obtained either from the Z forms (by the hydrochloride method) or isolated by column chromatography. Often, the reagents that have been used for oximation of aldehydes and ketones also catalyze the interconversion of Z and E isomers. The rate of equilibration of a mixture of Z and E isomers and the position of the equilibrium is temperature-dependent ". In 2001, Sharghi and Sarvani reported a convenient method for controlling the stereochemistry of the reaction of hydroxylamine hydrochloride with aldehydes or ketones in the solid state. The highly stereoselective conversion of aldehydes and ketones to their corresponding oximes... 

The most general method for synthesizing amines involves the reduction of oximes and imine derivatives obtained from aldehydes or ketones (see Sections 5.5.2 and 4.3.11). By catalytic hydrogenation or by LiAltLj reduction, while 1° amines are prepared from oxime or unsubstituted imine, 2° amines are obtained from substituted imine. Unsubstituted imines are relatively unstable, and are reduced in situ. 

This compound may be used to form oximes of aldehydes and ketones without alkali because the aqueous solution has a pH of about 5 at which the maximum rate of formation of oximes occurs. It is prepared conveniently from the chloride as follows ... 

Reaction CXXVII. Action of Acids, Acid Chlorides, Anhydrides, and Phosphorus Pentachloride on Oximes. (B., 23,11 J. C. S., 117,1045.)— Aldoximes (oximes obtained from aldehydes) exist in two stereoisomeric forms depending on the relative position of the OH group. 

The reaction serves for the production of amines from aldehydes or ketones through the oximes of these bodies. 

Functionalization of the carbon radical resulting from cyclization of an aminium radical is an important step for synthetic chemists in order to obtain the desired product directly or to provide a handle for further transformations. Radical reactions of A-chloroalkenylamines (Section III,B) lead to /3-chloro pyrrolidines, which are prone to rearrangement to give piperidines. Reactions of N-nitroso alkenylamines lead to 8-nitroso pyrrolidines and, if an a-hydrogen is present, ultimately to oximes of aldehydes or ketones. Advantages of the latter transformation are the formation of stable substituted pyrrolidines and the utility of the oxime moiety in regard to further transformations. 

Hydrolysis of 2-unsubstituted 1-azirines is a potentially valuable method for the preparation of aminoaldehydes. The application of the Neber reaction to oxime tosylates derived from aldehydes does not give the aminoaldehydes.59 Instead, nitriles are produced by elimination. 

The reaction with NH2OH is the formation of an oxime from the aldehyde and hydroxylamine and was dealt with in Chapter 14. The reaction with P2O5 is a dehydration—phosphorus is used to remove water from the oxime. 

There are two important routes to these compounds, both of which feature interesting chemistry. Oximes, easily made from aldehydes with hydroxylamine (NH2-OH), are rather enol-like and can b chlorinated on carbon. 

The adducts derived from aldoximes and carbodiimides are not stable. They undergo dissociation to give nitriles 472. This reaction is a useful synthetic route to produce nitriles from aldehydes and hydroxylamine in the presence of DCC and cupric salts in one step. The reaction of of the oximes with carbodiimides is best conducted in a two phase system (methylenechloride/water) using triethylamine, and the yields are almost quantitative." ... 

Functional groups containing the C = N bond, such as hydrazones, oximes and diazo compounds, can also be used in the synthesis of fluorinated derivatives and these reactions are the subject of this section. The reaction products in these procedures are usually the corresponding g cw-difluoromethylene compounds. Since oximes and hydrazones arc obtained from aldehydes and ketones, these reactions can be considered as an alternative to the direct transformation of a carbonyl group into the difluoromethylene group. As indicated in Section... 

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