Amination reactions secondary structures

These Br nsted-type plots often seem to be scatter diagrams until the points are collated into groups related by specific structural features. Thus, p-nitrophenyl acetate gives four separate, but parallel, lines for reactions with pyridines, anilines, imidazoles, and oxygen nucleophiles.Figure 7-4 shows such a plot for the reaction of trans-cmmm c anhydride with primary and secondary aliphatic amines to give substituted cinnamamides.All of the primary amines without substituents on the a carbon (R-CHi-NHi) fall on a line of slope 0.62 cyclopentylamine also lies on this line. If this line is characteristic of normal behavior, most of the deviations become qualitatively explicable. The line drawn through the secondary amines (slope 1.98) connects amines with the structure R-CHi-NH-CHi-R. The different steric requirements in the acylation reaction and in the model process... 

Schiffbase, 1147 Scurvy vitamin C and, 772 sec-Butyl group, 84 Second-order reaction, 363 Secondary alcohol, 600 Secondary amine, 917 Secondary carbon, 84 Secondary hydrogen. 85 Secondary structure (protein), 1038-1039... 

The Pd-catalyzed amination reactions <98AC(E)2046 01JOC2560> of 3,5-dibromo-2-pyrone 38 provided an array of structurally novel 2-pyrones with primary and secondary, aromatic and aliphatic amines at C3 in a highly regioselective manner (Scheme 32) <03TL95>. 

There are three structural types of amines, as discussed in Chapters 5 and 27 primary amines (RNHg), secondary amines (R2NH), and tertiary amines (RgN). Base strength differs for these amines and also for two different secondary amines or two different tertiary amines. A comparison of ammonia (NHg) with methanamine (27 methyamine) shows that 27 is more basic. In the reaction of 27 with water, the conjugate acid is ammonium salt (28) and the conjugate base is the hydroxide. The for this reaction is small, as indicated by the equilibrium arrows this means that the equilibrium lies to the left. A consequence of this observation is that the hydroxide ion is more basic than amine... 

Owing to the flexible nature of the secondary structure of the acid forms and group A salts, polar molecules such as alcohols and amines are readily absorbed into the solid bulk by substituting water mol ciiles and/or by expanding the interdistance between polyanions. Heteropoly acids which have absorbed a significant amount of polar molecules resemble in a sense a concentrated solution and are in a state between solid and solution. Therefore, this state is called the pseudo-liquid phase . Some reactions proceed mainly in this bulk phase. The tendency to form a pseudoliquid phase depends on the kind of heteropoly compound and the molecules to be absorbed and on the reaction conditions. 

Enamine (Section 17.11) Product of the reaction of a secondary amine and an aldehyde or a ketone. Enamines are characterized by the general structure... 

The oxidation of amines by mercuric acetate is an old reaction (54) which up until recent years was employed primarily to modify alkaloid structures (55). A systemic study of the oxidizing action of mercuric acetate by Leonard and co-workers led to the development of a general method for the synthesis of enamines from cyclic tertiary amines. An observation made after a large number of compounds were oxidized, but which is worth noting at the onset, is that a tertiary hydrogen alpha to the nitrogen atom is removed preferentially to a secondary a-hydrogen. 

A recent adaptation of the procedure employing perchlorate and fluoro-borate salts has been reported by Leonard and Paukstelis (J5). This report includes proof of structure by direct comparison to iminium salts prepared by protonation of enamines. The general reaction reported was that of a ketone or aldehyde with a secondary amine perchlorate to give iminium salts. A large structural variety of carbonyl compounds and several amine... 

In the reactions of benzyne with enamines, arylated enamines or amino-benzocyclobutenes can be obtained, depending on reaction conditions and the structure of the enamine. Thus the presence of a proton source such as a secondary amine will favor the enamine product through capture of the zwitterionic intermediate, whereas in the absence of protons one sees... 

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