1.1- Enediamines reactions

Although no direct evidence was found in the cobalt-N-hydroxyethylethyl-enediamine reaction that an oxygen-cobalt addition complex was formed, it seems reasonable to postulate that such an intermediate is present in the reaction. An oxygen-cobalt complex intermediate appears to afford the most logical method of explaining the evidence that the oxidation of cobalt (II) to cobalt (III) occurs in conjunction with the oxidative cleavage of the carbon-carbon bond of the hydroxyethyl group and the formation of ethylenediamine. 

Dimethyl acetylenedicarboxylate (80) undergoes initial 1,2 cycloaddition with acyclic enamines to form cyclobutene intermediates which immediately decompose into acyclic dienaminodiesters (94,95). When an acyclic n/c-enediamine is used instead of a simple acyclic enamine, a dienediamino-diester is produced via a cyclobutene intermediate (95a). A cyclization reaction of dimethyl acetylenedicarboxylate with an acyclic enaminoketone... 

This reaction is so facile that it is of value both for preparative and characterization purposes, Benzil and phenanthraquinone are convenient reagents for the characterization of o-diamines, and o-phenyl-enediamine is used commonly for the characterization of ff-dicarbonyl compounds. 

For quantitative work, it is necessary to estimate the concentration of 5-amino-l-(P-D-ribofuranosyl)imidazole in aqueous solution. It seems that the only available method is the Bratton-Marshall assay, which was originally developed for the estimation of arylamines in biological fluids. The principle of the method is the spectrometric estimation of a salmon-pink colored dyestuff obtained by diazotation in situ, followed by coupling with /V-( 1 -naphthyl)ethyl-enediamine.65 The only remaining problem then is to know the molar extinction of this dye because pure samples of AIRs are not available. A value of 16800 at 520 nM was obtained for the dyes prepared from a model compound, 5-amino-l-cyclohexylimidazole-4-carboxylic acid (54), which is crystalline. A comparable molar extinction can be expected for the dye prepared from imidazole 55, if the carboxyl group does not exert too much influence on the chromophore. Actually, its influence is perceptible even with the naked eye, the dyestuff prepared from 53 having a somewhat different, wine-red color, with max>520 nM. The molar extinction for 55 is 17400 at 500 nM. When the decarboxylation of 54 was conducted under mild acidic conditions (pH 4.8, 50°C, 1 hour), estimation of 5-aminoimidazole 55 by the Bratton-Marshall method led to the conclusion that the reaction was almost quantitative.66 Similar conditions for the final decarboxylation were adopted in the preparation of samples of AIRs labeled with stable isotopes.58... 

The most widely applied precursors for the synthesis of monocyclic NHPs are a-diimines which can be converted to the target heterocycles either in a two-step reaction sequence involving two-electron reduction of the diimine to an enediamide, enediamine, or a-aminoamine and subsequent condensation with PC13 [18-20] or a dichlorophosphine RPC12 [21], or via direct base-promoted reaction with PC13 [20, 22], The latter reaction involves addition of a P-Cl bond to each imine moiety followed by base-promoted elimination of hydrogen chloride leading to 2,4-dichloro-... 

The two-electron reduction of a-diimines to prepare the required starting materials for a subsequent condensation is usually achieved by reaction with lithium but other alkaline (Na) or alkaline earth (Mg) metals should be useful as well. The synthesis of the heterocycles 10 is either accomplished by direct metathesis of the formed metal enediamide with PC132 [19] or, alternatively, by quenching the diamide with a suitable acid to produce an enediamine or a-aminoimine, respectively, and subsequent base-induced condensation with PC13 or RPC12 [18, 20] (Scheme 3). 1,3-l )i-/e/t-butyl-2-chloro-1,3,2-diazaphospholene was also prepared from the reaction... 

Although this reaction was discussed earlier, it is mentioned here because it is catalyzed by solid acids such as NH4SCN, which provide H+ ions that bond to the pairs of electrons after breaking them loose from the metal. Over a rather wide range of catalyst concentrations, the rate is linearly dependent on the amount of solid acid. Once the NH4+ ion donates a proton, NH3 is lost and the protonated ethyl-enediamine molecule is the acid that remains and continues to catalyze the reaction. While base catalyzed reactions of complexes may be better known, there are many acid catalyzed reactions as well. 

If one end of a chelate ring on an octahedral complex is detached from the metal, the five-coordinate transition state can be considered as a fluxional molecule in which there is some interchange of positions. When the chelate ring reforms, it may be with a different orientation that could lead to racemization. If the chelate ring is not symmetrical (such as 1,2-diaminopropane rather than ethyl-enediamine), isomerization may also result. For reactions carried out in solvents that coordinate well, a solvent molecule may attach to the metal where one end of the chelating agent vacated. Reactions of this type are similar to those in which dissociation and substitution occur. 

Better yields are obtained when polar solvents are utilized and an amine such as tetramethylethyl-enediamine is present, which also facilitates the formation of the dilithium compound. The lithium derivatives undergo a large number of reactions that can be used to produce the enormous number of ferrocene derivatives. Rather than trying to show a great number of reactions, a few of the common reactants and the substituents that they introduce on the cyclopentadienyl rings are shown in Table 21.3. 

Bisdihydrodiazepinium salts have been obtained from reactions of ethyl-enediamines with a 4 f-pyrandialdehyde the latter in aqueous solution is an equilibrium with a bismalonaldehyde (77M929). 

Reaction of l-azirine-3-methylaciylates (155) with imidazoles and pyrazoles under mild conditions results in the formation of 2-aza-1,3-dienes (156), which are useful as dienes in hetero Diels-Alder reactions with electron-deficient dienophiles <99JOC49>. When the related methyl 2-aryl-2ff-azirine-3-carboxylate (157) was used as fee substrate, reaction with an amine induced a ting opening by addition of the amino group onto fee C=N bond followed by cleavage to provide enediamine 158 <99JCS(P1)1305>. 

Dr. Anbar First, concerning hydride transfer, our information shows that with longer chained diamines, say 1,3-propylenediamine and certainly, 1,4-butyl-enediamine, the catalytic. effect of copper disappears. With a longer chain the coordination is essential for the reaction. Then, an internal hydride transfer has to be assumed, that is an intramolecular and not extramolecular process. 

Reactions of this type have been much used, particularly in the preparation of monocyclic diazepines and 1,5-benzodiazepines by the reactions of ethylenediamine and o-phenyl-enediamine respectively with a variety of 1,3-bis electrophilic reagents. 

The reaction of dimethyl acetylenedicarboxylate with o-phenyl-enediamines yields 3-methoxycarbonylmethylene-2-oxo-1,2,3,4-tetra-hydroquinoxalines, e.g., 12.14-16... 

Bridged 1,5-benzodiazepines (204), prepared by condensation of o-phenyl-enediamine with 4,6-dimethylbicyclo[3.3.1]nona-3,6-diene-2,8-dione, give barbaralanes (205) on electrochemical reduction in acetonitrile in the presence of acetic anhydride338 [Eq. (119)]. The reaction is akin to the reduction of acetylacetone in which cyclopropane derivatives have been formed.339-340... 

Scheme 3 illustrates intriguing enantioselection in organic reactions that proceed in chiral crystalline lattices (5). When inclusion crystals of a ketone and an optically active diol host are treated with BH3-ethyl-enediamine complex, the optically active alcohol is obtained in... 

At present, researchers are attracted to the reactions of various enamines, enediamines, and related compounds with azadienes containing... 

The reaction of five-membered cyclic N,N-acetals results in ring expansion with CO incorporation to give cyclic enediamines with no silyl moiety. No reaction is observed for alkyl-substituted cyclic N,N-acetals. Cyclic N,0-... 

In the following, a series of preparations of dianionobis(ethyl-enediamine)cobalt(III) compounds, all starting with (carbonato)-bis(ethylenediamine)cobalt(III) chloride are given. (Carbonato )bis-(ethylenediamine)cobalt(III) chloride has been prepared with a high yield (80%) by a new method based upon the use of cobalt(II) chloride and the equivalent amount of (2-aminoethyl)-carbamic acid. The carbonato compound is easily converted into a number of dianionobis(ethylenediamine)cobalt(III) compounds with high yields. In some of the following procedures it was possible to use the carbon dioxide-ethylenediamine reaction mixture directly. 

Omeprazole was prepared [19] by reaction of 4-methoxy-o-phenyl-enediamine 1 with potassium ethyl xanthogenate 2 to give 5-methoxy-2-mercapto-lH-benzimidazole 3. Treatment of compound 3 with 3,5-dimethyl-4-methoxy-2-chloromethyl pyridine 4 in sodium hydroxide... 

Polyamides are polymers that contain the amide group and are produced, by, for example, polymerization reaction of adipic acid and hexamethyl-enediamine (HMDA). Nylon 6,6 (so-called because each of the raw material chains contains six carbon atoms) was the first all-synthetic fiber made commercially. 

A word of caution at this point seems most desirable. In every case where a pure aldonic acid or its derivative has been heated with o-phenyl-enediamine and an excess of hydrochloric acid, only a single benzimidazole has been isolated. It is well known that aldonic acids are epimerized by heating them at temperatures above 100° with organic bases such as pyridine. The heating of an aldonic acid with o-phenylenediamine at 135-150° may also result in appreciable epimerization. Thus, Moore and Link20 reported that from the fusion of xylonic acid with o-phenylenediamine at 150°, in the absence of mineral acids, they could isolate the epimeric lyxo-benzimidazole. Barker, Farrar, and Gulland,21 in a more detailed study, proved conclusively that both D-ribo- and D-arabo-benzimidazoles were formed when the condensation of calcium D-ribonate with o-phenylenediamine was carried out in the presence of less than two molecular equivalents of hydrochloric acid, whereas with an excess of hydrochloric acid only the D-ribo-benzimidazole was obtained. It is important, therefore, in the condensation of o-phenylenediamine with an optically active acid at an elevated temperature that the reaction mixture always be kept on the acid side. 

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