Amines sec., cyclic

It is known that the general structural characteristic of chelating ligands is a particular position of the donor atoms when the metal-cyclic polyhedra of coordination compounds are formed. The chelating N-donors are widely represented by Ai-(582), tri- (165,166,) tetra- (170-173), and penta- (174-177) amines (Sec. 2.2.4.2). Among diamine ligands, ethylenediamine (en) and its C- and N-substituted derivatives 585 are the most used [1] ... 

Several substituted cyclic sulfites have been prepared by the reaction of glycidol with a suitable sec-amine to furnish an amino diol, which is then treated with thionyl chloride in the presence of a base such as pyridine or triethylamine. This strategy of preparation of cyclic sulfites is of commercial importance because amine-substituted cyclic sulfites have been used as intermediates in the pharmaceutical industry (82JAP(K)82/02246 84JAP(K)59/07186 85MIP2 86JAP(K)61/227578). 

A wide variety of cyclic monomers have been successfully polymerized by the ring-opening process [Frisch and Reegan, 1969 Ivin and Saegusa, 1984 Saegusa and Goethals, 1977]. This includes cyclic amines, sulfides, olefins, cyclotriphosphazenes, and IV-carboxy-oc-amino acid anhydrides, in addition to those classes of monomers mentioned above. The ease of polymerization of a cyclic monomer depends on both thermodynamic and kinetic factors as previously discussed in Sec. 2-5. 

After the amines, acid anhydrides constitute the next most commonly used reagents for curing epoxy monomers. The epoxy-acid reaction proceeds through a stepwise mechanism (Sec. 2.2.4) while the reaction of epoxides with cyclic anhydrides, initiated by Lewis bases, proceeds through a chain-wise polymerization, comprising initiation, propagation, and termination or chain transfer steps. Some of the postulated reactions are shown in Table 2.25 (Matejka et al., 1985b Mauri et al., 1997). 

Fleischmann et al s 34 report cyclic voltammetry data for the oxidation of a series of aromatic hydrocarbons in a molten salt electrolyte, AlCl3-NaCl-KCl at 150°. Electrooxidation in this medium occurs at unusually low oxidation potentials. Tris-(p-substituted phenyl)amines, with the exception of tri (p-nitrophenyl) amine, yield very stable radical cations by all electrochemical criteria 380>S42 Mono- and bis-p-substituted triphenylamines, however, dimerize with rate constants ranging from 101 to 10s M 1 sec 1 to benzidines 176 (Eq. (237)), which subsequently are oxidized to the radical cations 177, whose ESR-spectra are observed. Dimerization is fastest with the p-N02 andp-CN-derivative, in accordance with HMO calculations, which predict the highest spin sensity in the p-position of these compounds 542 ... 

Figure 9. Cyclic voltammetric data for selected amines of environmental interest (carbon paste electrode, 200 mV/sec, pH 4.0 citrate buffer, 10% ethanol (v/v))...

In order to study the exceptional blue shift of absorption maximum for dimethyl-amine, the inclusion with azophenol crown 4 was carried out for a series of sec. amines in ethanol. Table 3 shows maxima of some sec. amine-4 systems. There, marked blue shifts are observed for 4 (n = 1) and 4 (n = 2) with pyrrolidine and piperidine. Such a blue shift for both cyclic amines disappears with the increase of crown size. 

To confirm the inclusion mode for a sec. amine, the 1 1 piperidine 4 (n = 1) complex was isolated and its molecular structure was determined by X-ray analysis (Fig. 10) [22], The chromophore is planar (except the o-nitro group) within 0.1 A, to which the cyclic polyether ring extends perpendicularly. The protonated piperidine having a chair form structure is placed on the crown ring and stabilized by very short N+ —H—O- (2.65 A) and N+ —H—O (2.93 A) hydrogen bonds, and two N + —O ion-dipole interactions (3.17 and 3.16 A). The remaining ether oxygen, 0(2), seems to be ineffective on the complexation. 

Sec- and fert-acyclic and cyclic amines A-Alkyl and N,A-dialkylarylamines Hydrazines Primary amines... 

As shown in the table, chiral substrale.s, amines, or aldehydes are employed in synthesis. Cyclic derivatives can also be obtained according to the reaction schemes reported in Sec. C.4. 

Pipen fie, C17H19O3N, is an alkaloid found in black pepper. It is insoluble in water, dilute acid, and dilute base. When heated with aqueous alkali, it yields piperic acid, C12H10O4, and the cyclic secondary amine piperidine (see Sec. 31.12), CsF N. 

Protection of primary amines. Primary amines form the cyclic adducts 2 ( Stabase adducts ) on reaction with 1 and a base (triethylamine for amines with pK 10-11, tt-butyllithium for less basic amines). The adducts are stable to n- and. sec-BuLi (-25°), LDA, H20, CH3OH, KF, and NaHC03 but unstable to HOAc, HC1, KOH, and NaBH. ... 

Fig. 18. Cyclic voltammograms of (top) ferrichrome A (pH 8) (middle) ferriox-amine B (pH 8) (bottom) ferric enterobactin (pH 10.5). All are in 1 M KC1, 0.05 M sodium borate/0.05 M sodium phosphate buffer. All cyclic voltammograms were at hanging mercury drop electrode with 100 mV/sec scan rate...

If the cyclic sulfate is initially opened with a sec-amine, the intramolecular displacement leads to a quaternary aziridine ion 229, which can be opened by a second nucleophile in a sequential triple displacement (95TL9241) leading to substituted amines 230, as shown in Scheme 58. 

Cyclic sec. amines from azidoboronic acid esters... 

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