Schiff bases, reduction

In a total synthesis of inhibitors of this kind, the following methods have so far been employed successfully (a) reaction of a cyclohexenyl halide with an amine, (b) coupling of an amine with an epoxide, and (c) condensation of an amine with ketone and reduction of the resulting Schiff base (reductive alkylation of an amino sugar). 

Scheelite, 25 349-350 Scheelite sorting, 16 626 Scheibel column, 10 777-778 Scheibler filter, 11 364 Schiff base(s), 21 203, 204, 25 100-101 chelating agents, 5 712t reaction with amino acids, 2 567 reaction with aniline, 2 786 thermochromic materials, 6 622-623 Schiff base chemistry, 24 42 Schiff base (reductive amination) method, for covalent ligand immobilization, 6 396t... 

As noted earlier, most classical antidepressant agents consist of propylamine derivatives of tricyclic aromatic compounds. The antidepressant molecule tametraline is thus notable in that it is built on a bicyclic nucleus that directly carries the amine substituent. Reaction of 4-phenyl-l-tetralone (18) (obtainable by Friedel-Crafts cyclization of 4,4-diphenyl butyric acid) with methyl amine in the presence of titanium chloride gives the corresponding Schiff base. Reduction by means of sodium borohydride affords the secondary amine as a mixture of cis (21) and trans (20) isomers. The latter is separated to afford the more active antidepressant of the pair, tametraline (20). 

Cyanogen bromide method A,A -Carbonyl diimidazole method Divinylsulfone method Epoxy (bisoxirane) method Ethyldimethylaminopropyl carbodiimide method Eluoromethylpyridinium toluenesulfonate method A-hydroxysuccinimide ester method Schiff base (reductive amination) method Tresyl chloride/tosyl chloride method Sulfhydryls Azalactone method (for azalactone supports)... 

Schiff base (reductive amination) method Nucleic acids Carbodiimide method... 

An example of diazepinone formation by lactamization is given by Da Settimo et al. <1999JHC639>. After reacting 8-aminotheophylline 50 with 2-carboxybenzaldehyde to form a Schiff base, reduction with NaBH4 forms precursor 51, which can be easily cyclized by heating at 300°C in a Pyrex tube to give 52 in 64% yield (Scheme 7). If the overall reaction is considered starting from theophylline, it could also be classified as a type eg bond formation. 

Secondary Amines Condensation of a primary amine with a ketone or aldehyde forms an /V-suhsti tuted imine (a Schiff base). Reduction of the imine, using either LiAlH4 or NaBH4, gives a secondary amine. 

The absolute configuration of the structurally unique fungal metabolite mycosporins was determined in the laboratory of J.D. White by means of enantioselective total synthesis." In the endgame of the synthetic effort, the Staudinger reaction was used to elaborate the side chain. The cyclic vinyl azide was first converted to a stable vinyl iminophosphorane, which was subsequently reacted with benzyl glyoxylate to afford the corresponding Schiff base. Reduction of the imine was achieved with sodium cyanoborohydride. 

SDS-polyacrylamide gel electrophoresis. The substrate specificity was rather loose with the protein portion ADP-ribosyl histones HI and H2B, peptide fragments of H2B, and nonhistone proteins (a mixture) served as substrates. In contrast, the specificity was very tight with the mono(ADP-ribosyl) portion and the carboxyl ester bond poly- or oligo(ADP-ribosyl) histones were hardly split, and ADP-ribose histone adducts formed chemically through Schiff base reduction [3] or ADP-ribosyl arginine bond formed by avian erythrocyte ADP-ribosyltransferase [14] did not serve as substrate. 

This technique applies to all nucleic acids. We originally pursued reduction due to the formation of Schiff bases with aldehyde addition to amino groups. A number of adducts may be chemically unstable as in a keto- or imine-state. Further, a number of aldehydes are unstable in addition reactions as Schiff bases. Reduction will stabilize these new adducts formed, and afford new and recognizable spots and their/ /. The fifth base analysis is based on a new demonstrable dNMP (J = 5.0,2.0 Figure 4 and 5), which seems to be a product of d AMP based on subtraction analysis by Ambis, where dAMP is diminished by as many counts as appears in the new base. Further, a proliferation of small adducts are revealed around the origin. Lastly, our candidates for Hm-dUMP and d(TG)MP are obliterated by reducing the hydroxyl moieties to water. 

Complementary information was gained from structural investigations of the E. coli transaldolase (EC 2.2.1.2) at 1.87 A resolution [41], including those on its covalent complex with dihydroxyacetone, which had been trapped at the active site Lys N by Schiff base reduction [42]. 

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