Alicyclic amines structure

TABLE 2. Structural parameters of the amino group in some alicyclic amines... 

The action of ammonia, primary and secondary amines on alkoxymethyleneiminium salts or alkylmercaptomethyleneiminium salts affords amidinium salts. Provided the educts are chosen in such a manner that the substitution pattern of the resulting amidinium salts does not exceed that of A/jV.AT -trisubstituted salts, the amidines can be released from the salts by addition of bases (see also Section 2.7.2.5.3). Very often the alkoxymethyleneiminium salts were prepared in situ and reacted without further purification with the amino compound to give the desired amidine. This amidine synthesis is of special synthetic interest, since it was stated that formamidines, derived from alicyclic amines, e.g. (306 equation 164), which are simple to obtain by this method, are readily transformed to reactive carbanions. Heterocycles, e.g. (307 equation 165), containing amidine structures, are accessible by reaction of appropriate difunctional compounds with iminium salts. ... 

As discussed in Section 7.4, conformational control in deamination of open-chain amines is difficult to evaluate because the activation energies of conformational changes are often smaller than those of the steps in deamination reactions. Alicyclic amines are more suitable for such mechanistic investigations. In addition, the con-formers of such amines can be locked if they contain bulky substituents (tert-hvXyX) or if the amines are based on bi- and polycyclic hydrocarbons (decalinamines, cholestaneamines, norbornylamines, etc.). We shall therefore concentrate first on the deamination of the epimeric 4-( er butyl)cyclohexylamines. Then, we will discuss the structural problems of cyclic carbocations formed in deamination of norbor-nylamine, cyclopropylmethylamine, and cyclobutylamine, i. e., compounds that are at the center of interest in the debate on classical versus nonclassical carbocations. 

The /ra 5-4a-decalyl amides (XIX) were the most thoroughly investigated group since the highest activities were found in this type. Unlike the alicyclic amines so far reported tra 5-4a-decalylamine was completely inactive, but as the size of the amide group increas so did the activity. Some indication of the relation between structure and activity in this series can be gained from Table 4.2, which contains a selection of the 110 compounds examined. 

The formation of the diazonium ion does not involve the asymmetric center, but the carbonium ion, if existing for any length of time, would be expected to assume a planar configuration. The neutral diazo compound cannot, of course, be optically active. Huckel (1938), who has carried out extensive investigations on the stereochemistry of this reaction, using alicyclic amines, has indeed observed extensive racemizations in many instances. However, in some cases configuration was fully retained, while in others there was almost complete inversion. It is as yet impossi ble to interpret these varying results, or to define the structural factors which determine the stereochemical result of this reaction in the case of these amines. 

To solve this question, a kinetic study was carried out wifli NPBS and a series of alicyclic amines 3-6. The study revealed that the reaction behaves in a different way regarding the type of amine employed. The structures of amines 3-6 togetiier wi their p a values are indicated in Fig. 17.1 ( a is the acidity constant of the conjugate acid of the bases employed). 

DCA is the first bile acid whose inclusion ability was confirmed in the crystalline state. During the last century many research groups dealt with the inclusion compounds of DCA with various guest molecules, such as aliphatic, aromatic and alicyclic hydrocarbons, alcohols, ketones, fatty acids, esters, ethers, nitriles, peroxides and amines, and so on [2], In 1972, Craven and DeTitta first reported the exact crystal structure of DCA with acetic acid [3], Subsequent crystallographic studies made clear that most of DCA inclusion crystals have bilayer... 

Here, we report on the use of trisamides as electret additives in i-PP. A general structure of these compounds is shown in Fig. 15. The molecules have a C3-symmetry and consist of a central core, three units capable of forming hydrogen bonds, and nonpolar peripheral substituents. The central core can be a triphenyl-amine, benzene, or cyclohexyl unit. The hydrogen bonds are in most cases formed via amide groups and the peripheral substituents consist of alicyclic or aliphatic linear or branched hydrocarbons. The direction of the linkage between the core and the one, two, or all three substituents can be inverted so that either the carbonyl or the amine groups are attached to the core. 

The configuration of the amines obtained in the hydrogenation of alicyclic ketoximes depends strongly on the pH of the medium, the catalyst used, and the structure of the substrate. 

Kinetic studies of Michael addition of alicyclic secondary amines to ethyl propiolate in H2O and MeCN have demonstrated a substantial solvent effect on reactivity and transition-state structure. The amines were found to be less reactive in MeCN, although they are by 7-9 units more basic in the aprotic solvent. The reaction rates for morpholine and deuterated morpholine proved to be identical, which rules out both a stepwise mechanism in which proton transfer would occur in the RLS and a concerted mechanism in which nucleophilic attack and proton transfer would occur through a four-membered cyclic transition state. Consequently, a stepwise mechanism with proton transfer occurring after the RLS is probable. Br0nsted-type plots were found to be linear with = 0.29 and 0.51 in H2O and MeCN, respectively, indicating that bond formation is not advanced significantly in the RLS. The small value is also consistent with the absence of isotope effect. ... 

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