Addition reactions of amines

The reactions shown in (4) proceed through the intermediate formation of substituted carbarnic acid, e.g. 

Frequently this is not of kinetic significance (see, however. Section 5) on account of the rapid decomposition of carbamic acid. Naturally stabiliza- 

These may be prepared by the reaction of the NCA with a primary or secondary base of which the strength is sufficiently high to ensure that no unreacted base remains. In these circumstances isolation and purification of the oligomer is not necessary. The absence of termination can be checked by estimation of basic end-groups. 

Nucleophilic attack of base on 2-CO as in (5) occurs relatively infrequently and constitutes a possible termination step. Since it results in the destruction of amine it has been detected by a diminution in the free base concentration. However, observation of such a decrease is not necessarily a dis ostic indication of mechanism (5) since it may also arise from other reactions (Section 7). 

Since the process represented by reactions (4a) and (4b) is a simple addition polymerization it leads to a distribution of molecular weights of the Poisson type [2]. At any st e of the reaction the concentration of polymer molecules containing n a-amino acid units [P ] is given by 

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In addition to being more basic than arylammes alkylammes are also more nucleophilic All the reactions m Table 22 4 take place faster with alkylammes than with arylammes The sections that follow introduce some additional reactions of amines In all cases our understanding of how these reactions take place starts with a consideration of the role of the unshared electron pair of nitrogen... 

The Michael addition reaction of amines and thiols with bismaleimides or functionalized monomaleimides is a versatile tool ia the synthesis of chain-extended maleimide-terroinated prepolymers. These prepolymers generally are soluble ia organic solvents from which they can be processed to prepreg and molded to high quaUty, void-free laminates. 

In addition to alkenes and alkynes, allenes have attracted considerable interest due to their unique reactivity and multireaction sites. Therefore, transition-metal-catalyzed nucleophilic addition reaction of amines and imines to allenes has been extensively studied to prepare biologically important amines and nitrogen-heterocycles.31,31d... 

The kinetics and thermodynamics of the addition reactions of amine and N-heterocyclic ligands to [0s04] have been studied using UV/Vis and NMR spectroscopies. With py, 4-pic, and bpy, the kinetics are too fast to be studied without using stopped-flow techniques, whereas the... 

The addition reactions of amines to polycarbonyl compounds are important ways of making heterocyclic compounds. An example is the condensation of ammonia with hexane-2,5-dione to give 2,5-dimethylpyrrole. 

Very efficient Michael addition reactions of amines, thiophenoi and acetylacetate to chalcone in a water suspension medium have been developed as completely organic solvent-free reactions. 

In the nucleophilic addition reactions of amines to substituted aromatic aldehydes where acid catalysis is required, the use of EAN seems to be convenient. The EAN can take part in an acid-base equilibrium with the aromatic aldehydes substituted by electron-withdrawing groups. The imine products from the selected aldehydes could be obtained, confirming the dual behaviour of EAN as Brbnsted acid and potential nucleophile in these type of processes (Fig. 13.7). 

Resin Types and Structure Typical Bisphenol Epoxy Resins Reactions of Epoxides and Curing Mechanisms Addition Reactions of Amines... 

Scheme 6.10 Aza- or thia-Michael addition reactions of amines or thiols...

Michael/Henry/dehydration/aromatisation reaction of 2-(2-oxoethyl) benzal-dehydes and nitroalkenes mediated by pyrrolidine to obtain polysubstituted naphthalene derivatives. DBU catalysed the conjugate additions of alcohols to ot,p-unsaturated nitriles, esters and ketones. Perhaps more important are the aza-Michael addition reactions of amines to a,p-unsaturated ketones, nitriles and esters. Recently, Costa, Vilarrasa and coworkers described the addition of lactams, imides, 2-pyridone, pyrimidine-2,4-diones and inosines to methyl propiolate and other similar compounds, DABCO and DMAP being the best catalysts. As mentioned before, tertiary amines give zwitterionic species with activated allynes. It was as early as 1932 when Diels and Alder used the reaction of pyridine with dimethyl acetylenedicarbojylate (DMAD) for the synthesis of heterocycles. The interception of the corresponding intermediate with Al-tosylimines and activated olefins provided access to l-azadienes ° and highly substituted butadienes (Scheme 2.6). When the quenching species of the zwitterionic intermediate is a 1,2-diketone, dibenzoyl maleates or cyclopentenedione derivatives could be obtained (Scheme 2.6). The interception of the zwitterionic species of N-methyl imidazole (NMI) and DMAD with ketenes to obtain unsaturated esters has also been shown. ... 

Very efficient Michael addition reactions of amines, thiphenol and methyl acetoacetate to chalcone in water suspension have been developed." For example, stirring a suspension of powdered chalcone in a small amount of water containing n-Bu NH and a surfactant, hexadecyltrimethylammonium bromide for 2 hr gave the adduct in 98% yield. Similarly adducts were obtained with thiophenol and methyl acetoacetate (Scheme 30). 

The addition reactions of amines and hydrazines, or derivatives of them, with carbon disulphide constitute common routes to dithiocarbamates and... 

Several comprehensive reviews of photochemical SET reactions of amines are available, as are more specialized reviews of the reactions of amines with specific classes of excited states. - These include reviews of the photochemical reactions of amines with arenes and iminium ions, which appeared in the first edition of this Handbook. The present article provides an overview of the photochemical addition reactions of amines with alkenes. Detailed information about the mechanisms and dynamics of these reactions is provided in the original literature and the comprehensive reviews. 

The photochemical addition reactions of amines to alkenes have provided a remarkably fertile area for synthetic and mechanistic investigations for over three decades. Each decade has brought the discovery of signihcant new reactions. Much of the body of work described in this review now appears to be complete, including the authors own work on stilbene-amine and styrene-amine reactions. Thus, as we pause to take stock of what has been accompHshed, we look forward to discoveries of new reactions and mechanistic insights. 

The Michael addition reaction of amines to conjugated double bonds is also used in the preparation of polyamine dendrimers, as shown in Scheme 3 [5]. This method is reported by Voegle and co-workers as the fundamental method for dendrimers synthesis and is termed cascade synthesis [6]. In this case, as shown in Scheme 3, the core and building block were 1,3-diamino-propane and acrylonitrile, respectively. After the Michael addition reaction, the terminal nitrile groups were catalytically hydrogenated to an amino group in the presence of Ni-Co catalyst. Thus, the nitrile group is the synthon (equiva-... 

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