Lactam and acid amide acetals. 63. Reaction of amide acetals with enaminodicarbonyl compounds

Corresponding dienediaminodicarbonyl compounds were synthesized by the reactions of a series of dimethylaminomethylenedicarbonyl compounds with N,N-dimethylacetamide and N-methylcaprolactam diethylacetals. In the reaction of N-methylvalerolactam diethylacetal, the process is accompanied by a rearrangement with the formation of a 3-methylenepiperidon-2-one derivative. It was found that the introduction of a substituted amino group into the meso-position of the intermediate -alkoxyenamine (in the preparation of dienediaminodicarbonyl compounds) takes place intermolecularly, and a general scheme of the unusual reaction studied has been proposed.For communication 62, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 218–223, February, 1991.     

2,4,6-Trichloropyrimidine. Reaction with sodium amide

The first reaction between 2,4,6-trichloropyrimidine 1 and anionic nitrogen nucleophiles is described. Treatment of 1 with one equivalent of sodium amide gave mixtures of 4-amino-2,6-dichloropyrimidine 2 and 2-amino-4,6-dichloropyrimidine 3 . Additional quantities of sodium amide failed to provide either diamino- or triaminopyrimidines. Instead, the strongly basic nature of sodium amide led to higher molecular products that were not characterized.     

The dynamics of conformational isomerization in flexible biomolecules. I. Hole-filling spectroscopy of N-acetyl tryptophan methyl amide and N-acetyl tryptophan amide

The conformational isomerization dynamics of N-acetyl tryptophan methyl amide (NATMA) and N-acetyl tryptophan amide (NATA) have been studied using the methods of IR-UV hole-filling spectroscopy (HFS) and IR-induced population transfer spectroscopy (IR-PTS), which were developed for this purpose. Single conformations of these molecules were selectively excited in well-defined NH stretch fundamentals. This excess energy was used to drive conformational isomerization. By carrying out the infrared excitation early in a supersonic expansion, the excited molecules were recooled into their zero-point levels, partially refilling the hole created in the ground state population of one of the conformers, and creating gains in population in other conformers. These changes in population were detected using laser-induced fluorescence downstream in the expansion. In HFS, the IR wavelength is fixed and the UV laser tuned in order to determine where the population went following selective infrared excitation. In IR-PTS, the UV is fixed to monitor the population of a given conformation, and the IR is tuned to record the IR-induced changes in the population of the monitored conformer. Besides demonstrating the capability of the experiment to change the downstream conformational population distribution, the IR-PTS scans were used to extract two quantitative results: (i) The fractional populations of the conformers in the absence of the infrared, and (ii) the isomerization quantum yields for each of the six unique amide NH stretch fundamentals (three conformers each with two amide groups). The method for obtaining quantum yields is described in detail. In both NATMA and NATA, the quantum yields show modest conformational specificity, but only a hint of vibrational mode specificity. The prospects for the hole-filling technique for providing insight into energy flow in large molecules are discussed, leaving a more detailed theoretical modeling to the adjoining paper [Evans et al. J. Chem. Phys. 120, 148 (2004)].     

Lactam and amide acetals. 56. Synthesis of pyrimidines from N-carbamoylamidines

N-Carbamoyl-N,N-dimethylformamidine reacts with ethyl anthranilate to give quinazoline-2,4-dione, and with cyanoacetamide to give 4-amino-5-carbamoylpyrimidin-2-one. The reaction of dimethylacetamide diethyl acetal with urea proceeds via N-carbamoyl-N,N-dimethylacetamidine with the subsequent formation of 4-dimethylamino-6-methyl-pyrimidin-2-one and 4,6-dimethyl-sym-triazin-2-oneFor Communication 55, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 81–84, January, 1990.     

Synthesis and Characterization of Poly(meta-aryl sulfide amide amide)

Poly(meta-aryl sulfide amide amide) (m-PASAA) was prepared with aromatic nucleophilic substitution reaction: by the step polycondensation of sodium sulfide(Na₂S· xH₂O) with 3,3′ -bis(4-diflurobenzoyl) aryl diamine between 180–202°C at atmospheric pressure. The polymers were characterized by FT-IR spectrum, ¹H-NMR spectrum, ¹³C-NMR spectrum, X-ray diffraction, element analyzer, DSC, TGA, AFM, instron universal tester and dissolvability experiment. The intrinsic viscosity of m-PASAA was 0.41–0.46 dl/g obtained with optimum synthesis conditions. The polymers were found to have excellent thermal performance with glass transition temperature (T_g) of 233.5–277.8°C, initial degradation temperature (T_d) of 447–456.7°C. They could afford flexible and strong films with tensile strengths 38.4–46.1MPa. At the same time, their solubility was much better than polyphenylene sulfide (polyphenylene sulfide scarcely dissolves in whole organic solvents under 200°C (1 Yang, J. 2006. PAS resin and its application, China: Chemical Industry Press.  [Google Scholar])).     

Methyl­malon­amide and ethyl­malon­amide

In the title compounds, C₄H₈N₂O₂, (I), and C₅H₁₀N₂O₂, (II), respectively, the amide groups are rotated out of the central C—C—C plane by ca 76° in (I) and by 70–73° in (II). Compound (I) has crystallographic mirror symmetry perpendicular to the molecular plane.     

Studies on the amide compounds ofMirabilis. Jalapa. L

Mirabilis himalaica(Edgew.)Heinerl Var. Chinensis Heimerl belonging to the genus Mirabilis are used in chinese medicine as a remedy for various diseases[1].Its chemical constituents,however, have not been reported so far. we have carried out a detailed chemical investigatigation of the seeds and have isolated two new amides along with three known compounds. The known compounds were identified by comparing their spectral data with those of authentic samples or with those reported in literature as daucosterol[2], bsitoserol[2], boeravinone E[3], in the present note, the structural elucidation of two new amides is reported.     

Investigation of aromatic-backbone amide interactions in the model peptide acetyl-Phe-Gly-Gly-N-methyl amide using molecular dynamics simulations and protein database search.

Weakly polar interactions between the side-chain aromatic rings and hydrogens of backbone amides (Ar-HN) are found in unique conformational regions. To characterize these conformational regions and to elucidate factors that determine the conformation of the Ar-HN interactions, four 4-ns molecular dynamics simulations were performed using four different low-energy conformations obtained from simulated annealing and one extended conformation of the model tripeptide Ac-Phe-Gly-Gly-NH-CH(3) as starting structures. The Ar(i)-HN(i+1) interactions were 4 times more frequent than were Ar(i)-HN(i+2) interactions. Half of the conformations with Ar(i)-HN(i+2) interactions also contained an Ar(i)-HN(i+1) interaction. The solvent access surface area of the Phe side chain and of the amide groups of Phe1, Gly2, and Gly3 involved in Ar-HN interactions was significantly smaller than in residues not involved in such interactions. The number of hydrogen bonds between the solvent and Phe1, Gly2, and Gly3 amide groups was also lower in conformations with Ar-HN interactions. For each trajectory, structures that contained Ar(i)-HN(i), Ar(i)-HN(i+1), and Ar(i)-HN(i+2) interactions were clustered on the basis of similarity of selected torsion angles. Attraction energies between the aromatic ring and the backbone amide in representative conformations of the clusters ranged from -1.98 to -9.24 kJ mol(-1) when an Ar-HN interaction was present. The most representative conformations from the largest clusters matched well with the conformations from the Protein Data Bank of Phe-Gly-Gly protein fragments containing Ar-HN interactions.     

Vibrational relaxation pathways of amide I and amide II modes in N-methylacetamide

We studied the vibrational energy relaxation mechanisms of the amide I and amide II modes of N-methylacetamide (NMA) monomers dissolved in bromoform using polarization-resolved femtosecond two-color vibrational spectroscopy. The results show that the excited amide I vibration transfers its excitation energy to the amide II vibration with a time constant of 8.3 ± 1 ps. In addition to this energy exchange process, we observe that the excited amide I and amide II vibrations both relax to a final thermal state. For the amide I mode this latter process dominates the vibrational relaxation of this mode. We find that the vibrational relaxation of the amide I mode depends on frequency which can be well explained from the presence of two subbands with different vibrational lifetimes (~1.1 ps on the low frequency side and ~2.7 ps on the high frequency side) in the amide I absorption spectrum.     

Carboxylic acid to amide hydrogen bonding. 10-Oxo-semirubins

Using their amide (and pyrrole) groups, dipyrrinones act as hydrogen bonding receptors for carboxylic acids, as found in a large number of 10-oxo-semirubins (1-6). The latter can be synthesized readily by Friedel-Crafts coupling of 9-H dipyrrinones with half-ester acid chlorides or diacid dichlorides of α,ω-dicarboxylic acids, ranging from C₂ to C₁₀. With ω-oxo-alkanoic acid chains of C₅ or ≥C₅, intramolecular hydrogen bonding is observed. With acid chains <C₅ hydrogen bonding is not observed. Uncharacteristically (for dipyrrinones), 10-oxo-dipyrrinone acids (1-6) and their corresponding esters (1e-6e) remain monomeric in hydrogen bond promoting solvents.     

Studies on some newer polyhydrazides containing amide linkages. III

Novel polyhydrazides having inherent viscosities in the range of 0.24–0.38 dL g^?1 were prepared by polymerizing a series of hydrazides with different diacid chlorides in polar aprotic solvents. These polymers display a wide range of solubility in a number of solvents. They start decomposing at about 200°C in air. Results of differential thermal and thermogravimetric analysis show that a steep weight loss takes place mainly in the range of 300–440°C.     

Lactam and acid amide acetals. 58. New synthesis of 3-nitro-5-hydroxybenzofurans

Previously unknown 3-nitro-5-hydroxybenzofuran derivatives were obtained by condensation of p-benzoquinones with nitro enamines.See [1] for Communication 57.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 597–600, May, 1990.     

Novel ferrocene modified poly(amide ether amide)s and investigation of physical and thermal properties

A new diamine containing ferrocene group with preformed ether and amide units was prepared via reaction of 1,1′-ferrocenedicarbonyl chloride with two moles of 2,6-bis(5-amino-1-naphthoxy)pyridine. Polycondensation reactions of the prepared diamine with different aromatic and aliphatic diacid chlorides in the presence of trimethylchlorosilane (TMSCl) resulted in preparation of novel ferrocene modified poly(amide ether amide)s. The monomer and polyamides were characterized and the effect of trimethylchlorosilane (TMSCl) as activating agent on the polymerization reaction was studied. The physical and thermal properties of the polyamides including inherent viscosity, solubility, thermal stability and behavior, flame-retardancy and crystallinity of the polymers were studied. The polymers showed good thermal stability and flame-retardancy, and also improved solubility in polar aprotic solvents.     

Liquid chromatography-mass spectrometry of hydroxy and non-hydroxy fatty acids as amide derivatives.

A useful method for analyzing fatty acids by liquid chromatography-mass spectrometry with an atmospheric-pressure chemical-ionization interface system has been developed. The sensitivity of six kinds of palmitamide derivatives monitored by a single ion of [M+H]+ was, in decreasing order: N-n-propylamide greater than anilide greater than N,N-diethylamide, amide greater than N,N-diphenylamide greater than N-1-naphthylamide. Individual fatty acids were identified from a mixture of amide derivatives of authentic fatty acids from C16:0 to C30:0 on a mass chromatogram. This method was used to detect both hydroxy and non-hydroxy fatty acids. Many kinds of fatty acid, including hydroxy fatty acids of the rat brain, were detected in a single run.     

Anharmonicity of amide modes

The principal contributions to the anharmonic coupling of amide vibrations are explored with the objective of comparing recent experiments with density functional theory and evaluating simple models of mode coupling. Experimental information obtained by means of two-dimensional infrared spectroscopy (2D IR) is reasonably well predicted by the computed one- and two-quantum anharmonic modes of amide-A, -I, and -II types in mono-, di- and tripeptides. The expansion of the vibrational energy up to the cubic and quartic coupling of harmonic modes suggested criteria to assess how localized are the forces determining the anharmonicity. The off-diagonal anharmonicity between an amide-A and one other amide mode was shown to be mainly determined by forces involving only these two modes, whereas the off-diagonal anharmonicity of two amide-I modes in peptides depended significantly on forces due to motions other than those of the amide-I type. Both the diagonal and off-diagonal anharmonicities exhibit sensitivity to peptide structures. These results should prove useful in linking 2D IR experimental results to secondary structure. Further, the results are used to evaluate the vibrational exciton model for the mixed-mode anharmonicities of the amide-I transitions.