Imines structure

A wide variety of /3-lactams are available by these routes because of the range of substituents possible in either the ketene or its equivalent substituted acetic acid derivative. Considerable diversity in imine structure is also possible. In addition to simple Schiff bases, imino esters and thioethers, amidines, cyclic imines and conjugated imines such as cinnamy-lidineaniline have found wide application in the synthesis of functionalized /3-lactams. A-Acylhydrazones can be used, but phenylhydrazones and O-alkyloximes do not give /3-lactams. These /3-lactam forming reactions give both cis and /raMS-azetidin-2-ones some control over stereochemistry can, however, be exercised by choice of reactants and conditions. 

The piperideine derivatives have not been studied as extensively as the analogous pyrrolines (151,152). The imino structure has been established, for example, for the alkaloid y-coniceine (146) (46). The great influence of conjugation on the structure is seen with l-(a-picolyl)-6,7-methylenedioxy-3,4-dihydroisoquinoline (47), possessing an enamine structure, whereas the analogous 1-methyl derivative (48) possesses an imine structure according to infrared spectra (152,153). 

The early stages of the reaction of the quaternary salt can be regarded as proceeding in a manner exactly analogous to that by which the isoxazoles themselves are degraded, the j8-oxoketene imine structure (148) being one mesomeric form of a compound which could alternatively be formulated as a nitrilium betaine. However, by contrast with the products from the isoxazoles (i.e., enolates of /3-keto-nitriles), this is electrically neutral and susceptible to further nucleophilic attack. 

In an elegant series of reactions, it has been demonstrated that 1//-azepines can be forced into adopting the benzene imine structure 8 by bridging the 2- and 7-positions with a trimethyl-ene chain.61 The length of the alkyl chain, however, is critical and the tetramethylene derivative exists solely as the 2,7-bridged l//-azepine (see Section 3.1.1.4.1.3.). 

This approach finds experimental support in FTIR measurements of the oxidation of PANI in organic solvents which indicate an anion intercalation mechanism for the second oxidation step. However, the IR findings may also be interpreted as support for the formation of a protonated imine structure... 

Figure 11 Proposed poly(imine) structure observed on platinum anodes during polymerisation...

Nuclear magnetic resonance studies on meso-ionic l,2,4-triazol-3-ones (200) were used to examine their relationship to the alternative l,3,4-oxadiazol-2-imine structure (153). The effect of solvent polarity upon the ultraviolet spectrum of anhydro-3-hydroxy-1,4-diphenyl-1,2,4-triazolium hydroxide (200, R = = Ph, R = H) has been discussed... 

Based partly on UV-vis absorption but mostly on surface-enhanced Raman scattering (SERS) data, the electrochemical oxidation product from 9-hydroxyellipticine (9-OH-E) 13a at Pt and Ag electrodes and that from A -methyl-9-hydroxyellipticinium cation (NMHE) 13b at those electrodes and also by horseradish peroxidase-H2O2 were studied and their structures identified <1996JRS539>. The products, 9-oxoellipticine (9-oxo-E) 14a from 9-OH-E and A -methyl-9-oxoellipticinium cation (NMOE) 14b from NMHE both have quinone-imine structures readily identified from the vibrational analysis of their SERS spectra. 

Compounds 332a, b possess an azomethine imine structure and should undergo cycloaddition reactions.4208 Although dimerization of 332b has not been observed,335 dipolarophiles yield cycloadducts 444 and Michael adducts 445.420a The structure of the product obtained from methyl propiolate, an unsymmetrical acetylene, has been studied by NMR and shown to be 446.420b... 

Alkenamines, or enamines, R—CH=CHNH2, usually are not stable and rearrange readily to imines (Section 16-4C). An important exception is benzenamine (aniline), C6H5NH2, which has an amino group attached to a benzene ring. The imine structure is less favorable by virtue of the considerable stabilization energy of the aromatic ring ... 

Chen, C. S. H., N. Colthup, W. Deichert and R. L. Webb Formation of ketene-imine structures during polymerization of acrylonitrile with X-rays. Paper submitted to J. Polymer Sci. 

Grassie, N., and I. C. McNeill Thermal degradation of polymethacrylo-nitrile. IV. Formation and decomposition of ketene-imine structures. J. Polymer Sci. 33, 171-182 (1958). 

The imine structure within the substrate also has a significant influence on asymmetric induction in the salen-Cu(II)-catalyzed enantioselective alkylation... 

When heated at 150 °C, trimethylsilylmethylisonitriles undergo an isomerization into the corresponding trimethylsilylacetonitriles. The tris(trimethylsilyl) derivative, not very stable at this temperature, undergoes further isomerization to the ketene imine structure.161... 

An A/-acetylated product, whose formation involved conversion of the di-imine structure into a vinamidine, could be obtained from benzodiazepine... 

Based on the corrected bromine to nitrogen core-level spectral area ratios. Neutral imine structure. 

Crosslinked resins of polyethylene imine structure have been prepared by various methods, including the reactions of polyethylene imine with epichlorohydrine 14), with allyl chloride 15), with ethylene dibromide, 6) or dichloride 17), and with toluene diisocyanate l8>. 

A titration curve determined in 0.03 M NaCl at room temperature has been reported in the case of cro s-linked PVA 62). The shape of the curve is similar to that of the linear polymer. Cr< >< s-linked resins of polyethylene imine structure have been used to complex heavy m, tal ions from dilute solutions. The complex formation of these resins with metal ions was not thoroughly studied on a thermodynamic basis however, the authors 63) demonstrated that, from a practical point of view, at least one of these resins in column operations was able to concentrate Cu2+, Co2+ and Ni2+ from aqueous solutions, even in the presence of high concentrations of alkali- and alkaline earth metals. 

The phenomenon of photodinduced arylotropy is extended to periphenoxy derivatives of pyrazoloanthrones that have the quinone-imine structure (Scheme 19).4142... 

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