Diamines, nucleophiles

The discussion of the pyridinocryptands has not been restricted, since there are currently only a limited number of cryptands of this type. The major synthetic pathways utilized for their construction have been the condensation of diacyl halides with diamines, nucleophilic substitution of dihalides by glycolates, and quaternization-demethylation of diamines. 

This is another strategy for the synthesis of Qxs (Scheme 2.3, Table 2.2) apart from diketones with diamine nucleophile and is based on the initial imine formation through the condensation of one of the amino groups of the diamine with the carbonyl group of the a-bromoketone. This would be followed by intramolecular... 

This strategy has been also employed [83-86] to a limited extent (Scheme 2.10) with diamine nucleophile. A hiomimetic approach can be used to synthesize Qxs (entry 1, Table 2.4) using (3-CD as a catalyst. The use of trimethylsilyl chloride (TMSCl) as a catalyst has also been reported however, this method requires longer time and is applicable for only limited substrates (entry 2, Table 2.4). Other methods used the solid-supported catalyst sodium hexafluorophosphate bound Amberlite resin and micellar sodirrm dodecylsulfate (SDS entries 3 and 4, Table 2.4). 

Polyesterimide (applied to marketable products) is produced by dianhydride A and m-phenylene diamine nucleophilic substitution with further thermal cyclization. The first stage of the synthesis is obtaining polyesteramido acids (PEAA), performed in methylene chloride mixed with water, and the second stage is performed in melt. 

Polyetherimide synthesis has been achieved by reaction of a dianhydride containing an ether linkage with a diamine, reaction of a diamine containing an ether linkage with a dianhydride, or nucleophilic displacement of halo or nitro groups of a bisimide by bisphenol dianion (19,20). Such Pis exhibit good thermal stabiUty and melt processibiUty. 

Syntheses. The presence of the ether and imide functionahties provides two general approaches for synthesis. Polyetherimides can be prepared by a nucleophilic displacement polymerkation similar to the haUde displacement inpolysulfone synthesis or by a condensation of dianhydrides and diamines that is similar to normal polyimide synthesis (see POLYIMIDES). 

This scheme eliminates the process of converting bis(etherimide)s to bis(ether anhydride)s. When polyetherimides are fusible the polymerization is performed in the melt, allowing the monamine to distill off. It is advantageous if the amino groups of diamines are more basic or nucleophilic than the by-product monoamine. Bisimides derived from heteroaromatic amines such as 2-arninopyridine are readily exchanged by common aromatic diamines (68,69). High molecular weight polyetherimides have been synthesized from various N,lSf -bis(heteroaryl)bis(etherimide)s. 

Cycloahphatics capable of tertiary carbocation formation are candidates for nucleophilic addition of nitriles. HCN in strong sulfuric acid transforms 1-methyl-1-cyclohexanol to 1-methyl-1-cyclohexylamine through the formamide (47). The terpenes pinene (14) [2437-95-8] and limonene [5989-27-5] (15) each undergo a double addition of HCN to provide, after hydrolysis, the cycloahphatic diamine 1,8-menthanediamine (16) (48). 

Micha.elAdditions. The reaction of a bismaleimide with a functional nucleophile (diamine, bisthiol, etc) via the Michael addition reaction converts a BMI building block into a polymer. The non stoichiometric reaction of an aromatic diamine with a bismaleimide was used by Rhc )ne Poulenc to synthesize polyaminobismaleimides as shown in Figure 6 (31). 

The chemistry of this cure system has been the subject of several studies (44—47). It is now generally accepted that the cure mechanism involves dehydrofluorination adjacent to hexafluoropropylene monomer units. The subsequent fluoroolefin is highly reactive toward nucleophilic attack by a variety of curatives (eg, diamines, diphenols). 

The kinetics of the hydrolysis of some imines derived from benzophenone anc primary amines revealed the normal dependence of mechanism on pH with ratedetermining nucleophilic attack at high pH and rate-determining decomposition of the tetrahedral intermediate at low pH. The simple primary amines show a linear correlation between the rate of nucleophilic addition and the basicity of the amine Several diamines which were included in the study, in particular A, B, and C, al showed a positive (more reactive) deviation from the correlation line for the simple amines. Why might these amines be more reactive than predicted on the basis of thei ... 

Step 1 of Figure 29.14 Transimination The first step in transamination is trans-imination—the reaction of the PLP—enzyme imine with an a-amino acid to give a PLP—amino acid imine plus expelled enzyme as the leaving group. The reaction occurs by nucleophilic addition of the amino acid -NH2 group to the C=N bond of the PLP imine, much as an amine adds to the C=0 bond of a ketone or aldehyde in a nucleophilic addition reaction (Section 19.8). The pro-tonated diamine intermediate undergoes a proton transfer and expels the lysine amino group in the enzyme to complete the step. 

Amino-77/-dibenz[/),t/]azepin-7-ones, e.g. 7, prepared either by successive bromination, aminodebromination, and dehydrogenation of 5-tosyl-5A/-dihydro 7>,t/]azepin-7(6//)-ones, or by the oxidation of 6-ethoxy-6,7-dihydro-5//-dibenz 7>,r/]azepincs with lead(IV) acetate followed by aminodemethoxylation, on treatment with a bidentate nucleophile (e.g.. benzene-1,2-diamine or 2-aminobenzenethiol) yield the pentacyclic systems 8 and 9, respectively.27... 

Arylisoxazol-5(4//)-oncs 21 react with benzene-1,2-diamines to yield 4-aryl-l,5-benzodiaze-pinones 22 by elimination of hydroxylamine from the intermediate oximes. Unsymmetrically substituted benzene-1,2-diamines are attacked at the more nucleophilic amino group. Thus, 4-methylbenzene-1,2-diamine gives 7-methylbenzodiazepinones 22f-h, whereas 4-nitrobenzene-1,2-diamine gives 8-nitro compounds 22k-n. The benzodiazepinones are accompanied by minor amounts of 2-methylbenzimidazoles 23. Selected examples are given.275... 

TNT-based condensation monomers. The synthesis of these materials is presented humorously by Russian authors a as consequence of the end of the Cold War. The synthesis, based on a very easy nucleophilic displacement of an activated nitro group, offers many possibilities for the synthesis of diamines bearing a functional group.117... 

IV-methyl pyrolidinone is used in most cases. Figure 5.31 summarizes the main reaction which can take place during the process and the corresponding rate constant. The formation of diamide has also been evidenced.140 The reactivity is governed by the electron affinity of the anhydride and the ionization potential or basicity of the diamine (see Section 5.2.2.1). When a diacid with a low electron affinity reacts with a weak nucleophilic diamine, a low-molecular-weight is obtained, because the reverse reaction is not negligible compared with the forward reaction. 

Asymmetric nucleophilic allylic substitution has rarely been studied in its heterogeneous version, probably because of the difficulties encoimtered in properly stabilizing and recycling Pd(0) species. Nevertheless, some promising examples have been pubhshed. Lemaire et al. [143] studied the activity and enantioselectivity of various chiral C2-diamines for the asymmetric Pd-catalyzed transformation of various allyl acetates. The structures tested are represented in Scheme 58. 

These observations indicated that an intermolecular double condensation to give a bis N-(methylene-4-oxocoumarinyl)-l,4 aromatic diamine had occurred. Data from the elemental analysis indicated that the calculated and observed values were within the acceptable limits ( 0.4%) and in conformity with the assigned structure. In the addition of molar equivalents of 1,4-aromatic binucleophilic compounds to compound 72 we did not observe any heterocyclic compounds resulting from the further intermolecular nucleophilic attack on the single condensation product. Since the condensation of 3-(dimethylaminomethylene)-chromane-2,4-dione with aromatic binucleophilic compounds is the only route to the new coumarinic compounds, this represents a useful synthetic method. 

The suggested catalytic cycle for the diamine catalysts indicates that the NH group of the diamine plays a direct role in the hydride transfer through a six-membered TS.53 A feature of this mechanism is the absence of direct contact between the ketone and the metal. Rather, the reaction is pictured as a nucleophilic delivery of hydride from ruthenium, concerted with a proton transfer from nitrogen. 

It has been found that a number of bidentate ligands greatly expand the scope of copper catalysis. Copper(I) iodide used in conjunction with a chelating diamine is a good catalyst for amidation of aryl bromides. Of several diamines that were examined, rra s-yV,yV -dimethylcyclohexane-l,2-diamine was among the best. These conditions are applicable to aryl bromides and iodides with either ERG or EWG substituents, as well as to relatively hindered halides. The nucleophiles that are reactive under these conditions include acyclic and cyclic amides.149... 

When p-ethylaminobenzoate and N,N-dimethyl-p-phenylene diamine sulfate were similarly treated with the dibromosulfone (I) for 2 h, the yield was only 32% and 15% respectively (Figure 1). A possible explanation is that the nucleophilicity of these monosubstituted anilines is weaker than that of aniline while a Na2C03 1,4-HBr elimination reaction could be competing with the substitution reaction, leading to the lower yield (18). 

Diamines react with azolides to produce diamides in cases where the nucleophilicity, the steric situation, etc. for the two amino groups are similar. If this is not the case, azolides may react selectively to give monoamides, as the examples below illustrate. 

Other hydroxylic solid-phase supports such as cross-linked agarose are similarly activated with CDI or V V -carbonyldi-1,2,4-triazole. The activated matrices can then be smoothly coupled with AT-nucleophiles such as glycine, 6-aminohexanoic acid, diamines, or proteins. 212 ... 

The susceptibility of cyclodisilazanes to nucleophilic attack by aromatic amines has also been used to prepare silazane containing polymers. Polysilazane cyclo-linear chains with aromatic spacing groups, synthesized by polycondensations of difunctional cyclodisilazanes with bis-phenols and N.N -diorganosilane diamines, have been reported (13). 

The Michael addition of a nitrogen-centered nucleophile to nitroalkenes affords compounds that may serve as precursors of vicinal diamines, since the nitro group can be reduced to an amino function by reduction. The very convenient method for the preparation of 1,2-diamines is developed by the addition of C-ethylhydroxylamines to nitroalkenes followed by reduction with H2 in the presence of Pd/C (Eq. 4.24).30... 

---