Amine with carbonyl group, reaction

A slightly more comphcated reaction involves an addition followed by loss of water. An example is the reaction of primary amines with carbonyl groups to give substituted imines (Fig. 16.51). 

A number of compounds of the general type H2NZ react with aldehydes and ketones m a manner analogous to that of primary amines The carbonyl group (C=0) IS converted to C=NZ and a molecule of water is formed Table 17 4 presents exam pies of some of these reactions The mechanism by which each proceeds is similar to the nucleophilic addition-elimination mechanism described for the reaction of primary amines with aldehydes and ketones... 

The Maunich reaction of a ketone, an amine, and an aldehyde is one of the few three-component reactions in organic chemistry. Cyclohexanone, for example, reads with dimethylamine and acetaldehyde to yield an amino ketone. The reaction takes place in two steps, both of which are typical carbonyl-group reactions. 

Intramolecular condensation of phosphonate carbanions with carbonyl groups carried out under conditions of high dilution have been utilized in macrocycle syntheses. Entries 7 and 8 show macrocyclizations involving the Wadsworth-Emmons reaction. Entries 9 to 11 illustrate the construction of new double bonds in the course of a multistage synthesis. The LiCl/amine conditions are used in Entries 9 and 10. 

When the ratio of template to acid is close to 0.5, the viscosity of the product is more than 3 times higher than the viscosity of the polymer obtained without the template. PEO participates in the change of local concentration by interaction with carbonyl groups, but not in the activation. Solution of LiCl in N-methylpyrrolidone with PlOCeHsls was found very effective system for synthesis of amides by the direct reaction of acids with amines in the presence of polymeric matrix. High molecular weight poly(aminoacids) obtained by direct polycondensation reaction, promoted by triphenyl phosphite and LiCl in the presence of poly(vinylpyrrolidone), were synthesized by Higashi et al The results for polymerization of L-leucine in the presence of poly(vinyl pyrrolidone) are presented in the Table 6.3. 

Reaction of the imidazole (7-4) with the benzofuran derivative (6-7) leads to the displacement of the benzylic halogen and the formation of the alkylation product (8-1). Treatment of that intermediate with trifluoroacetic acid breaks open the urethane to afford the corresponding free amine. This is allowed to react with ttiflic anhydride to afford the trifluoromethyl sulfonamide (8-2). The ester group on the imdidazole is then saponified, and the newly formed acid is reacted with carbonyl diimidazole. Reaction with ammonia converts the activated carboxyl group to the amide. There is thus obtained the angiotensin antagonist saprisartan (8-3) [6]. 

Addition of primary amines to carbonyl groups has been the subject of extensive study, notably by Jencks and co-workers.91 The most striking feature of these reactions is the characteristic maximum in the graph of reaction rate as a function of pH.92 Figure 8.10 illustrates the observations for the reaction of hydroxylamine with acetone. It is also found that the sensitivity of rate to acid catalysis,93 and to substituent effects,94 is different on either side of the maximum in the pH-rate curve. These phenomena may be understood in terms of the two-step nature of the reaction. In acetal formation, we saw in Section 8.3 that the second step is rate-limiting in the overall process, and it is relatively easy to study the two steps separately here, the rates of the two steps are much more closely balanced, so that one or the other is rate-determining depending on the pH. 

Vinyl substitutions on alkenes not having their double bonds conjugated with carbonyl groups often proceed more rapidly and give better product yields when the reactions are conducted in the presence of an unhindered secondary amine. Conjugated and nonconjugated dienes are usually only minor products in these cases. The major products normally are allylic amines obtained by nucleophilic attack of the secondary amine upon the ir-allylpalladium intermediates. Since allylic amines may be quatemized and subjected to the Hoffmann elimination, this is a two-step alternative to the direct vinyl substitution reaction.90... 

In the classic carbohydrate chemistry addition reactions of carbonyl groups served as valuable tools for sturctural studies of carbohydrates. For example, hydroxyl amine, hydrazine, and phenyl hydrazine react with carbonyl groups to yield oximes and hydrazones. In the presence of an excess... 

Tire nitrogen atom in the pyridine ring is planar and trigonal with the lone pair in the plane of the ring. This makes it an imine. Most of the imines you have met before (in Chapter 14, for example), have been unstable intermediates in carbonyl group reactions, but in pyridine we have a stable imine—stable because of its aromaticity. All imines are more weakly basic than saturated amines and pyridine is a weak base with a pK of 5.5. This means that the pyridinium ion as about as strong an acid as a carboxylic acid. 

In contrast to the preceding carbonyl group reactions, cations [(CgHg)Mn(CO)3] and [(MegCg)Re(CO)3] reacted with primary amines with loss of the arene group to give derivatives of the type [(RNH2)3M(C0)3] 14). Arene replacement reactions have also been... 

The enrichment in nitrogen of humic substances extracted in EDA (Table 5) suggests that solvents containing this compound, or any other primary amine, would not be appropriate for use with humic substances. EDA readily reacts with carbonyl groups to form Schiff base structures. Such reactions are rapid when the protonated carbonyl group reacts with the nonpro-tonated amine. Thus the maximum reaction rate occurs when the product of the concentrations of the protonated carbonyl groups and free amines is maximum. The reaction continues, but at a rate which decreases in an exponential manner, as the pH is raised or lowered from the optimum value for the reaction. 

The course of the condensation reaction can be influenced by the presence of agents such as sodium hydrogen sulfite or hydrazine which react with carbonyl groups. For example, 2-phenylpyrimidine-4,5,6-triamine reacts with 2-oxopropanal at pH 7 to give 7-methyl-2-phenyl-pteridin-4-amine (3, 60%).51 However, when hydrazine is added to 2-oxopropanal prior to admixture with the pyrimidine, the only product which is obtained is 6-methyl-2-phenylpterid-in-4-amine (4).5 2... 

Insertions of vinylic palladium halides with olefins not conjugated with carbonyl groups is more complex. Rearrangement of the initial insertion product to a i-allyl-palladium derivative usually occurs as in Eq. (p). Since the a -allylic complexes are relatively stable, catalytic reactions to form dienes with tertiary amines as bases are slow and inefficient . A useful catalytic reaction occurs, however, if a nucleophilic secondary amine is used as base instead of the tertiary amine. The a-allylic palladium intermediates are attacked by the amine to form tertiary allylic amines and regenerate the catalyst ... 

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