Amides additions

Process economics dictate the recycling of the unwanted isomer. Path A in Figure A8.2 illustrates that racemisation of the D-N-benzylidene amino add amide is fadle and can be carried out under very mild reaction conditions. After removal of die benzaldehyde die D,L-amino add amide can be recyded 100% conversion to the L-amino add is theoretically possible. Another method for racemisation and recycling of the L-amino add (path B, Figure A8.2) comprises the conversion of the L-amino add into die ester in the presence of concentrated add, followed by addition of ammonia, resulting in the formation of the amide. Addition of benzaldehyde and racemisation by OH- (pH =13) gives the D,L-amino add amide. In this way 100% conversion to die D-amino add is possible. 

As predicted, the presence of cinnamic acid in solution caused cinnamide to crystallize as flat prisms with prominent 011 faces (Figure 4b). The crystal morphology was modified along c by the use of amide additives that contain a bulky Cl substituent at the a- or P-carbons of cinnamide. When replacing a substrate molecule, these additive molecules interfere with the deposition of the next Oil layers (Figure 3), yielding 011 platelike crystals (Figure 4d). 

There have been discussions whether the amide addition at C-6 is charge-controlled or orbital-controlled. Charge density calculations in 4-phenylpyrimidine (MNDO method) predict that the addition of the amide ion would preferably take place at position 2 (95UP1) this, however, does not agree with the experimental results. Therefore, the conclusion seems justified that the addition is not charge-controlled. Frontier orbital calculations, using the SCF-PPP method, show that the frontier orbital densities in the LUMO of pyrimidine are zero at C-2 and C-5, making these positions... 

Meyers and Shimano further expanded the scope of this methodology to include lithium amides as the nucleophile. The authors meticulously optimized the reaction conditions and determined the scope of the amide addition. Selected examples are listed in Table 8.32 (Scheme 8.163). The best results were obtained when THF was used as the solvent together with a stoichiometric amount of HMPA, relative to the lithium amide. The reaction was quite sensitive to the steric demand of the amide. Thus, lithium diethylamide give no product whereas lithium methyl n-pentylamide and lithium piperidide gave efficient reaction. Primary amides also failed to react. 

The authors proposed a chelating transition state model to explain these results (Fig. 8.14). The thermodynamically more stable intermediate resulting from initial lithium amide addition should have the amino group on the face opposite to the bulky tert-butyl group. Due to the same steric effect, the HMPA ligand should also occupy a position on the p face. The electrophile approaches the enolate from the ot face and gives the trans product. For bulky amines, either the aza enolate does not form due to severe steric hindrance or the aza enolate is inactive for the same reason. 

Very little information is available for monomeric sodium amides. Addition of pmdeta to NaN(CH2Ph)(CHMePh) effects its transformation into the monomeric l,3-diphenyl-2-azallyl salts [(pmdeta)NaN(CHPh)2] and (pmdeta) a (CHPh)(C lePh)J. " However, the sodium hydrazide salt [(thf)3NaN(Ph)N(SiMe3)2] crystallizes as monomers featuring... 

Kauffmann showed that treatment of halopyridines 34 with an excess of lithium dialkylamides at room temperature leads, via the intermediate 3,4-pyridyne (35), to an isomeric mixture of the amide addition products 36 and 37 (Scheme 11) [71AG(E)20]. Such reactions are inconsequential if they are performed at low temperatures where the rate of lithium halide elimination is slow. 

Michael addition to unsaturated amides. This system (1 equiv. of each) effects Michael addition of ketones, nitro compounds, ethyl cyanoacetate, and diethyl malonate to a,(3-unsaturated amides. Addition to methacrylamides is interesting because the final products are glutarimides or dihydropyridinones. 

Amides. All amides are characterised by a strong carbonyl absorption band, referred to as the amide I band. Primary and secondary amides additionally show bands arising from N—H stretching and bending vibrations. The N—H... 

Phthalic Acid or Phthalic Anhydride. Mixtures explode violently on heating.8 Sodium Amide. Addition of the nitrite to molten amide results in violent explosion.9 Sodium Thiocyanate. Mixture explodes on heating.6... 

To prepare 2-aminopyridine by treatment of pyridine with potassium amide in liquid ammonia at —33 °C and using permanganate as oxidant was not successful. No reaction takes place under these conditions. The aromaticity of the pyridine ring is too high to allow nucleophilic amide addition. It was surprisingly observed that treatment of a solution of 3-nitropyridine in liquid ammonia (thus without the presence of potassium amide) with potassium permanganate, gave after work-up a mixture of... 

On the other hand, the substrate may undergo nucleophilic attack by base, either in the rate-determining step — with or without formation of an intermediate — or in a fast pre-equilibrium step which is followed by rate-determining breakdown of the intermediate. These three possibilities are included in the B2 mechanism according to Ingold s nomenclature [14]. Examples of one-step B2 reactions (SN2 mechanisms) are the alkaline hydrolyses of sulfonic esters [14] and 2,4,6,-tri-f-butylbenzoic esters [18]. Intermediates are formed by carbonyl addition of hydroxide ion in the alkaline hydrolyses of (unhindered) carboxylic esters and amides. Addition of OH is partially or completely rate-determining in ester hydrolysis [4, 15], but probably not in amide hydrolysis [15]. 

Incompatible with alkalis, heavy metal ions, especially copper and iron, oxidizing materials, methenamine, phenylephrine hydrochloride, pyrilamine maleate, salicylamide, sodium nitrite, sodium salicylate, theobromine salicylate, and picot-amide. Additionally, ascorbic acid has been found to interfere with certain colorimetric assays by reducing the intensity of the color produced. ... 

Table 19. Viscosity maintenance in CDA- films containing carbazole sulphuryl amide additions in ultra-violet radiation...

Studying ultra-violet spectrums of indan derivatives let us make a supposition about their "shield" mechanism, which causes light stabilizing effect, as indan sulphuryl amide additions (as carbazolsulphonamides) absorb radiation in the same wave length interval as cellulose diacetate. 

For characterization and exploitation of the diamide-phase system, a chiral diamide, e,g., (Ill) was examined as a modifier in the mobile phase (solvent) in conjunction with a non-bonded (bare) silica. Such a chiral carrier separated enantiomeric N-acyl-d-amino acid esters and amides with separation factors comparable to those for bonded stationary phase systems. The resolution can be as cribed to diastereomeric complexation through amide-amide hydrogen bonding between the amide additive and enantiomeric solute molecules in the carrier solvent, followed by separation of the diastereomeric complexes by the (achiral) silica phase. This process should be applicable as widely as that involving chiral diamide-bonded stationary phase systems. 

Figure 6.9 Co-crystal structure of ATP bound to PI3K-y. The binding mode is characterized by the hinge region interaction of the purine ring nitrogen with the Val-882 backbone amide. Additional interactions shown are H-bonds from Ser-806 and Lys-833 to the phosphate and from the exocyclic amine to Glu-880.

Slip, antislip, and antiblock agents [30, 31] do not facilitate molding or semifinished product manufacture as do lubricants. What they do is to simplify further processing - of foils in particular. Foil bags that have been stored in stacks cannot be readily picked up or opened, problems that are particularly noted with LDPE and PP. An effective slip agent with LDPE is addition of 0.05 % oleic acid amide and with PP the same amount of eruca acid amide. Additive manufacturers supply concentrates of these compounds in granulate form for addition to molding compounds [50]. 

Oxidative aminations are possible at other quinoline and isoquinoline positions, even on the benzene ring, providing a nitro group is present to promote the amide addition. ... 

---