Imine nitrogen substituted

Reaction of A,A-dimcthylsullamoyl aziridines 323 and 325 with primary amines furnishes substituted 1,2,5-thiadiazolidine 1,1-dioxides 324 and 326, respectively, in a regioselective manner <06SL833>. Aziridine 325 is made from ( I /t,6,S ,Z)-bicyclo[4.2. l]non-3-en-9-one in two steps /V,/V-dimethylsulfamoyl imine formation using dimethylsulfamide and subsequent reaction with trimethylsulfoxonium ylide. The product from the reaction with 4-methoxy-benzyl amine can be subsequently manipulated (debenzylation and derivatization) to give the alternative nitrogen substitution pattern in a controlled manner. 

Formation of nitrones can be achieved in the first stage of a Krohnke type reaction in which p-n trosodi methy 1 an dine reacts with 2-oo-bromoacetylphenoxathiin in alkaline medium (336). The synthesis of a series of cyclic nitrones of structure (182) has been achieved by regioselective, and by an unusual [3 + 2] cycloaddition of a-nitrosostyrenes (181) to 1,3-diazabuta-l,3-dienes (180) (Scheme 2.64) (337a). Theoretical studies of the substitution effect at the imine nitrogen on the competitive [3 + 2] and [4 + 2] mechanisms of cycloaddition of simple acyclic imines with nitrosoalkenes have been reported (337b). 

Several pyridine containing ligands of this type have been reported by Toftlund [2]. A combination of two aliphatic and four imine nitrogen functions seems to provide a ligand field at the crossover point. A versatile class of ligands of this type is based on aliphatic diamines substituted with four alkylpyridine groups. The simplest compound of this type is tetrakis(2-pyri-dylmethyl)-l,2-ethanediamine (tpen) (18). 

Soil A reversible equilibrium is quickly established when aniline covalently bonds with humates in soils forming imine linkages. These quinoidal structures may oxidize to give nitrogen-substituted quinoid rings. The average second-order rate constant for this reaction in a pH 7 buffer at 30 °C is 9.47 x 10 L/g-h (Parris, 1980). In sterile soil, aniline partially degraded to azobenzene, phenazine, formanilide, and acetanilide and the tentatively identified compounds nitrobenzene and jD-benzoquinone (Pillai et ah, 1982). 

These examples illustrate that biomolecules may act as catalysts in soils to alter the structure of organic contaminants. The exact nature of the reaction may be modified by interaction of the biocatalyst with soil colloids. It is also possible that the catalytic reaction requires a specific mineral-biomolecule combination. Mortland (1984) demonstrated that py ridoxal-5 -phosphate (PLP) catalyzes glutamic acid deamination at 20 °C in the presence of copper-substituted smectite. The proposed pathway for deamination involved formation ofa Schiff base between PLP and glutamic acid, followed by complexation with Cu2+ on the clay surface. Substituted Cu2+ stabilized the Schiff base by chelation of the carboxylate, imine nitrogen, and the phenolic oxygen. In this case, catalysis required combination of the biomolecule with a specific metal-substituted clay. 

The nature of the iminic nitrogen substituent influences the cycloaddition pathway (4 + 2 versus 3 + 2) followed in the reactions of a-nitrosoalkenes with alkyl/aryl-substituted acyclic imines.4 The problem of rotamer control in Lewis acid-catalysed 3 + 2- and 4 + 2-cycloaddition reactions of a./S-disubstituted acryloylimides was solved by the use of N-H imide templates.5... 

Unactivated C-H bonds can be functionalized if a suitable directing group can be incorporated into a substrate. For example, an on/io-t-butylaniline derivative will react with a substituted benzaldehyde to give an imine. This imine nitrogen then directs cyclometalation of the t —butyl methyl group (equation 71). The resulting Pd-C bond is then able to undergo further functionahzation. 

This reaction depends on the type of nitrogen substitution and it is proposed that the reactivity may correlate with the ionization potential of the imine. Oxidized derivatives, i.e. the oxime (31 = OH) ... 

Synthetic and biological interest in highly functionalized acyclic and cyclic amines has contributed to the wealth of experimental methodology developed for the addition of carbanions to the caibon-mtrogen double bond of imines/imine derivatives (azomethines). While a variety of practical methods exist for the enantio- and stereo-selective syntheses of substituted alcohols from aldehyde and ketone precursors, related imine additions have inherent structural limitations. Nonetheless imines, by virtue of nitrogen substitution, add a synthetic dimension not available to ketones. In addition, improved procedures for the preparation and activation of imines/imine derivatives have increased the scope of the imine addition reaction. 

Imines and substituted oximes react with several nitrogen-containing nucleophiles to provide a general synthesis of diaziridines or diazirines. ... 

The Friedel Crafts (F C) reaction via activation of electrophiles functionalized by a nitrogen atom, such as imines, is undoubtedly the most practical and atom eco nomical approach to introduce a nitrogen substituted side chain to aromatic com pounds. The enantioselective version of the F C reaction of nitrogen substituted substrates, including imines, with electron rich aromatic compounds enables effi cient access to enantioenriched aryl methanamine derivatives [37[. Several excellent approaches to highly enantioselective F C reactions have been established using chiral phosphoric acid catalysts. 

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