Schiff bases acylation

Phosphorylglycines are easily prepared, but in limited yield, by alkoxycarbonylation of the a-lithiated Schiff base of diethyl aminomethylphosphonate in THF at low temperature. The acylated Schiff base is converted in high yield (80%) to the corresponding p-lactam by photochemical reaction with the [(methoxy)(methyl)carbene]chromium complexes in CHjCF. ... 

Structural alerts or chemical motifs known to be associated with toxicity through either the parent compound or reactive metabolites have also been used to predict potential toxicity from chemical structures. These expert algorithms appear in commercial software programs and in onhne open access sites. For instance, there are seven chemical domains that are used to define and predict the covalent interaction between a chemical and a macromolecule (biological target) that leads to an initiating event at the beginning of an AOP [34]. These include Michael addition, acylation, Schiff base formation, aromatic nucleophilic substitution, unimolecular... 

Elimination of the hydroxyaminomethyl moiety from nitro oxime 15 by treatment with a diazonium salt gave hydrazone 43 (75LA1029) (Scheme 15). The same product was obtained by coupling the diazonium salt with the compound 16. On heating in aniline, oxime 15 was transformed into Schiff base 42. Acylation of the oxime 15 with benzoyl chloride in pyridine led to a mixture of furazan 44 and dinitrile 45. 

As has been outlined for the Strecker synthesis, the Ugi reaction also proceeds via initial formation of a Schiff base from an aldehyde and an amine. The imine intermediate is attacked by the isocyanidc, a process which is supported by protonation of the imine by the carboxylic acid component. The resulting a-amino nitrilium intermediate is immediately trapped by the carboxylate to give an 6>-acyl imidiate. All steps up to this stage are reversible. Only the final oxygen to nitrogen acyl shift is irreversible and delivers the A-acyl-a-amino amide as the thermodynamically favored product which contains two amide groups. 

Recent progress of basic and application studies in chitin chemistry was reviewed by Kurita (2001) with emphasis on the controlled modification reactions for the preparation of chitin derivatives. The reactions discussed include hydrolysis of main chain, deacetylation, acylation, M-phthaloylation, tosylation, alkylation, Schiff base formation, reductive alkylation, 0-carboxymethylation, N-carboxyalkylation, silylation, and graft copolymerization. For conducting modification reactions in a facile and controlled manner, some soluble chitin derivatives are convenient. Among soluble precursors, N-phthaloyl chitosan is particularly useful and made possible a series of regioselective and quantitative substitutions that was otherwise difficult. One of the important achievements based on this organosoluble precursor is the synthesis of nonnatural branched polysaccharides that have sugar branches at a specific site of the linear chitin or chitosan backbone [89]. 

We succeeded in showing that recycling of the enzyme was indeed possible in our IL solvent system, though the reaction rate gradually dropped with repetition of the reaction process. Since vinyl acetate was used as acyl donor, acetaldehyde was produced hy the hpase-catalyzed transesterification. It is well known that acetaldehyde acts as an inhibitor of enzymes because it forms a Schiff base with amino residue in the enzyme. However, due to the very volatile nature of acetaldehyde, it easily escapes from the reaction mixture and therefore has no inhibitory action on the lipase. However, this drop in reactivity was assumed to be caused by the inhibitory action of acetaldehyde oligomer which had accumulated in the [bmim][PFg] solvent system. In fact, it was confirmed that the reaction was inhibited by addition of acetaldehyde trimer. =... 

Table 10 includes the results for skin irritation. No clear results have been obtained. All models are in agreement only for the absence of irritative potential of BDE 100. Multiple results from ToxTree are due to the five different alerts used by the model (Schiff base formation, SNAr, Acyl transfer agent, skin sensitization, and Michael acceptor). A global evaluation of ToxTree data could suggest that all the analyzed compounds are not able to induce skin sensitization. These predictions are in clear contrast with that obtained by applying CAESAR and in partial agreement with the results of Toxsuite. 

In 1991 Bose described the synthesis of ot-vinyl /1-lactams by reaction of ,/l-unsa-turated acyl chlorides with a Schiff base in chlorobenzene under microwave irradiation (an example of the eco-friendly MORE chemistry, in which only a limited amount of solvent is used) [20b]. Under these conditions, a-vinyl /1-lactam formation can be achieved in 65-70% in approximately 5 min (classical conditions require several hours and lead only to modest yields). 

A cobalt catalysed carbonylation reaction converts A-substituted 1-aza-1,3-dienes into A-allylacetamides by a reductive acylation process [31]. Acetamides are byproducts of the reaction. In contrast, Schiff bases undergo a double A,C-acetylation under the same conditions producing a-acetamido ketones and A,A-disubstituted acetamides [32],... 

Reduction of Schiff base (XXXI) formed between l-phenethyl-4-piperidone and aniline, and acylation of the resultant dibase gives the highly potent analgesic [112] fentanyl(Sublimaze,XXXIla). In mice (tail-clip method), fentanyl... 

Conversely, ester condensation reactions join acyl groups from CoA derivatives to Schiff bases derived from glycine or serine. Succinyl-CoA is the acyl donor... 

Pyrimidin-5-amine, 4-methylamino-synthesis, 3, 121 Pyrimidin-5-amine, 4-oxo-purine synthesis from, S, 582 Pyrimidinamines acylation, 3, 85 alkylation, 3, 86 basic pKa, 3, 60-61 diazotization, 3, 85 Dimroth rearrangement, 3, 86 electrophilic reactions, 3, 68 Frankland-Kolbe synthesis, 3, 116 hydrolysis, 3, 84 IR spectra, 3, 64 15N NMR, 3, 64 nitration, 3, 69 Principal Synthesis, 3, 129 reactivity, 3, 84-88 structure, 3, 67 synthesis, 3, 129 Pyrimidin-2-amines alkylation, 3, 61, 86 basic pKa, 3, 60 diazotization, 3, 85 hydrogenation, 3, 75 hydrolysis, 3, 84 mass spectra, 3, 66 Pyrimidin-4-amines acidity, S, 310 alkylation, 3, 61, 86 basic pKa, 3, 61 Schiff base, 3, 85 synthesis, 3, 110, 114 1,3,5-triazines from, 3, 518 Pyrimidin-5-amines basic pKa, 3, 61 hydrogenation, 3, 75 reactions... 

Hydrozirconation of imines.1 Reaction of Schiff bases containing an a-hydrogen with 1 followed by acylation provides a route to enamides and/or imides and amides. Examples ... 

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