Oxo compounds aldehydes

HOCH2CH2OCHS (Methyl Cellosolve) Alkoxyacetylenes M ethoxy acetyl en e Ethylene oxide Tetrahydrofuran Dioxane Glucose Hydroquinone Oxo compounds Aldehydes... 

Occasionally it happens that the oxo compound, produced by oxidation, forms a hydrate which is further oxidized to a dihydroxy compound. Attention must be given to the possibility (so far unreported) that when the hydrated species is in equilibrium with a trace of the ring-opened structure a sufficiently fast oxidation rate of the amino-aldehyde (i.e. the acyclic structure) could lead to the incorrect conclusion that the original material was not cyclic. 

The spectra of 1,3,5-, 1,3,7-, and 1,3,8-triazanaphthalerie cations revealed that they were predominantly hydrated, and mild oxidation to the corresponding 4-oxo compounds indicated that hydroxylation took place on C-4. Ring-chain tautomerism in the cation was excluded, at least during the first 45 min after mixing, because negative aldehyde tests were obtained with p-nitrophenylhydrazine. 1,3,6-Triazanaphthalene, under the same conditions, gave a yellow precipit-... 

In the cases of oxiranes, the formation of alcohols and oxo compounds (ketones and aldehydes) are the result of primary processes.3,274-286 Hydrogenation of oxo compounds does not occur on surfaces covered with oxirane. The adsorption of oxiranes on metal surfaces is irreversible during adsorption, ring-opening takes place also. As the temperature is raised, the proportions of the oxo compounds increase. 

Reactions of the type in Eq. (42) have been achieved with aldehydes and ketones [Eq. (43)] (9, 19). None of the intermediates according to Eq. (42) was isolated. A [2 + 2]-cycloaddition (step a) probably occurs, since [2 + 2]-cycloadducts can be isolated from the reaction of imino-boranes and oxoalkanes in particular cases (Section VI,A). As far as alkynes are concerned, addition of oxo compounds proceeds in the presence of BFj as a catalyst, but without a break of the CC <7-bond [in analogy to step c in Eq. (42)] rather polar alkynes are needed [Eq. (44)] (78). 

Reaction of aldehydes and ketones with iminoboranes has been widely investigated. Conditions for the [2 + 2]-cycloaddition between XBNR and R R"CO are relatively good stability of the iminoborane and lack of enolic protons in the oxo compound [Eq. (46)] 14, 19). Relatively less stable iminoboranes, but in some cases the stable ones too, may react with 0X0 compounds by a total opening of the B=N triple bond [Eq. (43)], presumably via a [2 + 2]-cycloaddition [Eq. (42)] (Section V,D). A relatively stable iminoborane and a ketone containing enolic protons may yield an open-chain product, probably through a six-membered cyclic transition state [Eq. (46b)] 19). 

The more usual cyclocondensations of two identical molecules of 1,3-dicarbonyl or other C-acidic components with a third different oxo compound (mostly an aldehyde) afford exclusively 4//-pyrans and resemble the well-known Hantzsch synthesis of 1,4-dihydropyridines. It usually proceeds... 

From a thermodynamic point of view, the hydrogenation of the C=C bond is more favorable than that of the C=0 group. Since there are numerous other important processes to synthesize saturated aldehydes and ketones, the main objective of recent research efforts is to increase the selectivity of hydrogenation of unsaturated oxo compounds into unsaturated alcohols. The results summarized below clearly indicate the significant success achieved in the selective hydrogenation of unsaturated aldehydes. The hydrogenation of unsaturated ketones, in turn, cannot be accomplished yet with similar selectivities. 

The Wittig reaction involves the interaction of an oxo compound (an aldehyde or ketone) (1) with phosphonium ylides [substituted methylene phosphoranes (2a,b)], through an intermediate betaine (3), to yield the appropriate alkene (4) and triphenylphosphine oxide (5), as shown in equation 1. 

Now let me come back to primary substitutions at the ferrocene nucleus. Together with Vil chevskaya, we phosphorylated ferrocene and its derivatives to triferrocenylphosphine oxides [263, 264). An unusual reaction, discovered in collaboration with Perevalova and Yur eva, was the direct cyanation of ferrocene with hydrocyanic acid in the presence of ferric chloride [265,272). Initially, cyanide attacks the iron atom of the ferricinium cation, then the cyanide group transfers to the ring while the iron is simultaneously reduced. The reaction was termed by us as the ricochet (from the metal to the nucleus) substitution it may be applied to many substituted ferrocenes and to the ruthenocenium cation [273), and it is now the simplest route to ferrocene carboxylic acids through their nitriles. Further, ferrocene was studied in acid-medium reactions with oxo compounds. With aldehydes [274), the reaction was complicated by the transformation of ferro-cenylalkyl carbinol formed Initially via the carbonium ion, followed by transformation to a radical which, in its turn, was coupled to 1,2-bis-(ferrocenylalkyl)ethane (27.5). The reaction with acetone led to 2,2-di-ferrocenylpropane (276). 

One possible explanation of the formation of the primary alcohol is that the oxirane isomerizes to aldehyde in the first step (Eq. 142) the aldehyde then being hydrogenated to alcohol. This is not probable, for oxiranes participate in hydrogenolysis under conditions where oxo compounds do not react at all with hydrogen or only very slowly moreover, the reduction of the oxo compound does not occur on a surface covered with the oxirane. Thus, formation of alcohols and oxo compounds is the result of simultaneous processes. 

The binuclear /x-oxo compound (Scheme 330) has been prepared and is readily isolated by chromatography. Subsequent treatment with SiXMe3 (X = C1, I, OTf) followed by transmetallation and desymmetrization reaction with the lithium salt of cyclohexadiene affords an excellent reagent for the transfer of cyclohexadienyl groups to various aldehydes.503... 

Methylmagnesium halide reacts stereospecifically with a 19-aldehyde (269) to give the (I )-19-methyl-19-ol (270), whereas lithium aluminium hydride reduced the 19-methyl-19-oxo-compound (271) to give the 19(S)-alcohol 212) Both reactions indicate a preferred conformation for the 19-carbonyl compound, with the carbonyl oxygen atom close to C-5. 

Aminotransferases catalyze the reversible exchange of a primary amino group between amino and oxo compounds, via a double-displacement reaction in which the cofactor shutties between its aldehyde and amino forms (Figure 18). Over a long period, AAT has been the most investigated PLP-dependent enzyme. It has been... 

Oxo compounds from halides via nitrones a,/5-Ethylene aldehydes... 

By the time comprehensive reviews by Wilds (29) in 1944 and Djerassi (30) in 1953 became available, MPV reactions were a standard reductive technique in the organic chemistry community. For example, a 1945 patent (20) describes the utility of using aluminum alkoxides in the presence of an organic nitrogen as a weak base for the reduction of carbonyl groups on oxo compounds such as 7-hydroxy-cholesterol acetate, benzaldehyde, cinnamic aldehyde, and citronellal. 

Various 2-oxo compounds have been subjected to a variety of reactions. Alkylation and acylation result in the formation of 1,3-disubstituted products.Similarly the Mannich reaction with morpholine gives products such as the bis compound 107. Halogenation of the 0x0 compound 108 with bromine in acetic acid," or chlorine in acetic acid, ° or with sulfuryl chloride results in formation of the monohalo derivatives 109. The chlorine atom in 109 (R = Cl) can be removed by hydrogenation over palladium on charcoal. Nitration of the chloro compound 110 with a mixture of nitric and sulfuric acids provides the nitro derivative 111, which may be catalytically reduced to the amino compound 112. If the reduction is carried out in the presence of an aldehyde, the product is a substituted amino derivative (113). Alternatively the amine 112 can be condensed with an aldehyde and the resultant Schiff base reduced to give the product 113. 

Many aldehydes, e.g.9 furfuraldehyde,317 can be reduced even in the cold in general, however, the reduction is carried out at elevated temperature in order that the usually volatile oxo compound may be removed by distillation. 

Oxo compounds - Compounds containing an oxygen atom, =0, doubly bonded to carbon or another element. The term thus embraces aldehydes, carboxylic acids, ketones, sulfonic acids, amides and esters. [5]... 

Beckmann fragmentation of the oxime of the 3-ketone (428) gives the unsaturated seco-nitrile (429) the derived epoxide (430) reacts with BFj-ether in boiling toluene to give the 4oe-methyl-5a-3-oxo-compound (432) in good overall yield. It seems likely that the cyano-aldehyde (431) is an intermediate the cyclization step could then involve the enol (433), with final hydrolysis and decarbonylation of the a-formyl-imine (434). 

The reactions of bromohydrins in the cholestane series with Ag20 have been shown to depend markedly on the conformation of the bromine. Thus, for example, the 6a-bromo-7 -hydroxy-compounds (107) and (108), which have the equatorial bromine, gave the B-nor-aldehyde (110) whereas the 6/8-bromo-7/S-hydroxy-compound (109) gave the 7-oxo-compound (111) via a hydride shift. Hydrolysis of the dipotassium 5)3-pregnane-3a,20a-diyl sulphate in 3N-HC1 gave the D-homo-steroids (112) and (113) in addition to the expected... 

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