Schiffbase

Schiffbase, 1147 Scurvy vitamin C and, 772 sec-Butyl group, 84 Second-order reaction, 363 Secondary alcohol, 600 Secondary amine, 917 Secondary carbon, 84 Secondary hydrogen. 85 Secondary structure (protein), 1038-1039... 

The dependency of the Schiffbase ligands 11-13 on the diastereoselectivity has been reported [27,28]. 

Formation of /1-lactams by the reaction of an acid chloride, a SchifFbase and a tertiary amine (Eq. 62) appears to involve multiple pathways, some of which are very fast at higher temperatures. When conducted in open vessels in unmodified micro-wave ovens, high level irradiation leads to preferential formation of the trans -lactams (55%) whereas, at low power, the cis isomer was obtained as the only product (84%). The failure of the cis isomer to isomerize to the trans compounds is an example of induced selectivity. 

Scheme 4.29 Reaction of the acid chloride of tetrachlorophthaloyl glycine with a Schiffbase.

Keywords Spin crossover Fe(III) Dithiocarbamate Thiosemicarbazone Schiffbase... 

Here the hapten (Scheme 2) is a 13-diketone, which incorporates structural features of both reactants - ketone donor and aldehyde acceptor (see below, Scheme 3) - in the aldol reaction of interest. In favorable cases the hapten reacts with the primary amino-group of a lysine residue in the complementary-determining region of an antibody to form a Schiffbase 5, which readily tautomerises to the more stable vinylogous amide 6. 

A single crystal ENDOR study comprising 1H-, 13C-, 14N- and 59Co-ENDOR investigations of the Schiffbase compound Co(acacen) (Fig. 42) doped into Ni(acacen) 1/2H20 was therefore undertaken by Rudin et al.12,59,61,219). As illustrated in Fig. 2b, ENDOR spectroscopy allows hf and quadrupole interactions of all the magnetic ligand... 

A simple, fast and specific color test for urea nitrate was reported recently by Almog et al. It is based on the reaction between urea nitrate and ethanolic solution ofp-dimethylaminocinnamaldehyde (p-DMAC) (9) under neutral conditions [91]. A red pigment is formed within 1 min from contact. Its structure has also been determined by the same group, by X-ray crystallography [92]. It appears to be a resonance hybrid between a protonated Schiffbase (10) and a quinoid system (10a) (Eq. (14)). The limit of detection on filter paper is 0.1 mg/cm. Urea itself, which is the starting material for urea nitrate, does not react with p-DMAC under the same conditions. Other potential sources of false-positive response such as common fertilizers, medications containing the urea moiety and various amines, do not produce the red pigment with p-DMAC. 

Fig. 2.2.2.4 Schematic representation of interactions of the reduced Schiffbase intermediate (red, boxed) with amino acid residues of the active site of transaldolase B. H-bridge bonds are shown by broken lines. The corresponding amino acid residues in...

Through a combination of experimental and theoretical calculations, Corma and coworkers proposed a mechanism for the hydrogenation of oleftnic molecules by gold catalysis. In this study, Au(III)-Schiffbase complexes proved to be as active as the corresponding Pd complexes. Some gold(III) intermediate species were proposed but were not detected [192]. 

Soloshonok and co-workers have developed a method for the synthesis of a-(perfluoro-alkyl)amines from perfluoroalkyl carbonyl compounds by a transamination involving an azomethine a/omethine (Schiffbase) isomerization. They call this method a biomimetic, base-catalyzed 1,3-proton shift reaction, and have applied it to perfluoroaldehydes,12-15 perfluoroalkyl ketones,12 18 / -(perfluoroalkyl)-/l-oxo esters,15 16 19 24 and - -( perfluoroalkyl)-a-oxo es-ters2 " -26 to synthesize the corresponding a-(perfluoroalkyl)amincs, / -(perfluoroalkyl )-/i-amino acids, and 3 -(perfluoroalkyl)- x-amino acids. 

Virtually all types of metal ions have been complexed with macrocyclic ligands.2-7 Complexes of transition metal ions have been studied extensively with tetraaza macrocycles (Chapter 21.2). Porphyrin and porphyrin-related complexes are of course notoriously present in biological systems and have been receiving considerable investigative attention (Chapter 22).8 Macrocyclic ligands derived from the Schiffbase and template-assisted condensation reactions of Curtis and Busch also figure prominantly with transition metal ions.6,7 The chemistry of these ions has been more recently expanded into the realm of polyaza, polynucleating and polycyclic systems.9 Transition metal complexes with thioether and phosphorus donor macrocycles are also known.2... 

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