Imines with 1,2-diamines

Macrocycles have been prepared by formation of macrocyclic imines as well as by using variations of the Williamson ether synthesis ". Typically, a diamine or dialdehyde is treated with its counterpart to yield the Schiff s base. The saturated macrocycle may then be obtained by simple reduction, using sodium borohydride, for example. The cyclization may be metal-ion templated. In the special case of the all-nitrogen macrd-cycle, 15, the condensation of diamine with glyoxal shown in Eq. (4.14), was unsuccess-ful ... 

The imine bond —CH=N— is formed during polycondensation of aromatic/aliphatic diamines with aromatic/ aliphatic dialdehydes ... 

The presence of ether linkages in the polymer molecule imparts chain flexibility, lowers glass transition temperature, and enhances solubility while maintaining the desired high temperature characteristics [192]. Recently, polyether imines were prepared by the reaction of different diamines with 4,4 -[l,4-phenylene bis(oxy)] bisbenzaldehyde [184]. The polymers synthesized by the solution method were yellow to white in color and had inherent viscosities up to 0.59 dl/g in concentrated H2SO4. Some of these polyimines can be considered as... 

The spiro compound 206 was prepared in five steps from (S)-l-naphthyl-ethylamine and was composed of a mixture of imine and enamine tautomers. Reduction of the imine function by sodium borohydride occurred on the less hindered si face, leading to the diamine with the R configuration of the newly formed stereo center, then the N-benzyl substituent was removed by hydrogenolysis to give 207 with good overall yield [98] (Scheme 30). 

Imines can be stereoselectively hy-drodimerized to 1,2-diamines with rac/ meso rahos of 0.9 to 1.1 similar to the cathodic coupling of carbonyl compounds to pinacols in an acidic medium [304]. With 4,6-dimethylpyrimid-2-one only the meso-diamine was obtained [305]. Electroreduction of diimines prepared from... 

The following two synthetic techniques are applied for obtaining complexes of aliphatic, aromatic, and heterocyclic imines in the limits of the discussed variant of the template synthesis interaction of coordinated mono- and diamines with mono- and dicarbonyl derivatives (method A) and reactions of complexes of o-hydroxyalde-hydes (ketones) with amines and diamines (method B). The simplest transformation of this type is represented by the reaction (3.176) [53,54] ... 

Fig. 9.27. Condensation of diamines with dicarbonyl compounds (and/or their hydrates) to give N heterocycles. Double imine formation yields quinoxalines (B), double enamine formation leads to dimethylpyrrole (D).

The oxazaborolidine-catalyzed reduction of 1,2-diketones (Equation (258)),1116-1120 1,2-keto-imines (Equation (259)),1121-1123 and 1,2-diimines (Equation (260))1124 provided optically active 1,2-diols, amino alcohols, and 1,2-diamines with both high enantiomeric and diastereomeric excess. The method can be also effective for (3- and y-analogs. 

Reacts violently with azides, CsNs, CIO, ethylamine diamine, ethylene imine, Pb(N3)2, LiNs, (H2SO4 + permanganates), KN3, RbNs, NaN3, phenylcopper-triphenylphosphine complexes. 

A coupling reaction similar to pinacol coupling has been used with imines, which dimerize to give 1,2-diamines. A number of reagents have been used, includ-... 

Cu-diimine macrocycle compounds (31) are formed by Jaeger template condensations of diamines with acyl-substituted /3-keto imines (30) (Scheme 9). The acyl substituents on the macrocycles are labile and undergo a variety of reactions. Reaction with trifluoromethyl sulfonate produces reactive methoxy ethylidene diimine compounds (32), which react with amines to form saddle-shaped cyclidenes. With bulky substituents these compounds have a hydrophobic void above the metal ion which can accommodate a guest molecule, an effect enhanced when the... 

Starting from a pyrimidine, sodium borohydride reduces the C=N bond in various 1,2,5,6-tetrahydropyrimidines to the hexahydro derivative <79RTC282>. Overreduction can be seen because C2 in the product, the hexahydropyrimidine, is an aminal carbon with the possibility for a dynamic equilibrium with imine and immonium forms which may be reduced to propane-1,3-diamines either by catalytic hydrogenation or by metal hydrides in the formation of an open-chain 1,3-diamine <67AJC1643, 68JA771>. 

The synthesis of carboxylate-substituted imidazoline derivatives has previously been accomplished by the condensation of presynthesized 1,2-diamines with amides, or through the transition metal catalyzed aldol-type reaction between isocyanates and imines (4,5). We have recently communicated an alternative palladium catalyzed route to synthesize a new class of imidazoline carboxylates, utilizing acid chloride, imines and carbon monoxide as starting materials (see Table 1)... 

In our conditions, we have only observed secondary imines and secondary amines. Moreover, we have shown that the C-N impurities are mainly produced during the hydrogenation of aminonitrile to diamine. They correspond to the reaction of primary diamine with aminoimine intermediate. 

Formation of pyrazines and quinoxalines has been a focal point of many years of study. The most common method to make these rings relies on the condensation of 1,2-diamines with 1,2-dicarbonyls in ethanol or acetic acid in 35-85% yields. The mechanism proceeds through a double imine formation. Recently improved methods have been reported, employing transition-metal catalysis and microwaves. ... 

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... 

The same research group [90] reported the preparation of OA (PAIs) derived from N,N-(4,4 -oxydiphthaloyl)-bis-(s)-(+)-valine diacid chloride. The polymers were prepared by the reaction of aromatic diamines with the diacid by classical low-temperature solution polycondensation (reaction time 2 h at -5°C and 8 h at rt), high-temperature polycondensation (reflux conditions, reaction time Imin), and MW polycondensation reaction (reaction time 6min). Comparable results were obtained for all polycondensation processes. 

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