2023-06

Theoretical Chemistry Accounts (Volume : 141)

investigated using molecular electron density theory (MEDT) at the MPWB95/6-311++G(d,p) computational level. This 32CA reaction undergoes two stereo- and stereoisomeric reaction paths to form two different products 3 and 4. An electron localization function (ELF) study predicts that the N-methyl-C-(4-hydroxylphenyl) nitrone 1 has a zwitterionic character and it takes place through a one-step mechanism, with activation enthalpies in between 17.48 and 23.41 kJ mol− 1 in the gas phase. The CDFT indices are used to forecast the global electron density flux from the strong nucleophilic N-methyl- C-(4-hydroxylphenyl) nitrone 1 to the electrophilic maleic anhydride 2. These exergonic 32CA reactions have negative Gibbs free energy along the endo and exo stereochemical routes. The endo stereochemical process is favored over the exo stereochemical pathway due to the increased thermodynamic stability of the cycloadduct. Bonding evolution theory (BET) predictions for the endo and exo routes indicate a one-step process with early transition states, which is consistent with the ELF topological investigation at the transition states.

2023-05

International Journal of Molecular Sciences (Volume : 24)

[3+2] cycloaddition reactions play a crucial role in synthesizing complex organic molecules and have significant applications in drug discovery and materials science. In this study, the [3+2] cycloaddition (32CA) reactions of N-methyl-C-4-methyl phenyl-nitrone 1 and 2-propynamide 2, which have not been extensively studied before, were investigated using molecular electron density theory (MEDT) at the B3LYP/6–311++G(d,p) level of theory. According to an electron localization function (ELF) study, N-methyl-C-4-methyl phenyl-nitrone 1 is a zwitterionic species with no pseudoradical or carbenoid centers. Conceptual density functional theory (CDFT) indices were used to predict the global electronic flux from the strong nucleophilic N-methyl-C-4-methyl phenylnitrone 1 to the electrophilic 2-propynamide 2 functions. The 32CA reactions proceeded through two pairs of stereo- and regioisomeric reaction pathways to generate four different products: 3, 4, 5, and 6. The reaction pathways were irreversible owing to their exothermic characters: −136.48, −130.08, −130.99, and −140.81 kJ mol−1, respectively. The enthalpy of the 32CA reaction leading to the formation of cycloadduct 6 was lower compared with the other path owing to a slight increase in its polar character, observed through the global electron density transfer (GEDT) during the transition states and along the reaction path. A bonding evolution theory (BET) analysis showed that these 32CA reactions proceed through the coupling of pseudoradical centers, and the formation of new C-C and C-O covalent bonds did not begin in the transition states.

2022-05

Journal of the Mexican Chemical Society (J. Mex. Chem. Soc.) (Volume : 66)

The zwitterionic-type (zw-type) [3+2] cycloaddition (32CA) reactions of N-methyl-C-3-bromophenyl-nitrone 1 with dimethyl maleate 2 with increased electrophilicity were investigated using the Molecular Electron Density Theory (MEDT) at the MPWB95/6-311++G(d,p) computational level. Both reactivity and selectivity are rationalized in relation to the polarity of the reaction. The associated zw-type 32CA reactions are accelerated due to the high nucleophilic character of N-methyl-C-3-bromophenyl-nitrone 1 and the strong electrophilic character of dimethyl maleate 2, which also play a critical part in the mechanism of the reaction, influencing the stereoselectivity, with activation enthalpies in between 34.04 and 38.37 kJ.mol-1 in the gas phase. The CDFT indices are used to anticipate global electron density flux from the nucleophilic N-methyl-C-3-bromophenyl-nitrone 1 to the electrophilic dimethyl maleate 2. These exergonic 32CA reactions havenegative Gibbs free energy along the endo and exo stereochemical pathways. The endo stereochemical processis preferred over the exo stereochemical pathway in this kinetically controlled 32CA reaction. The predictionsof bonding evolution theory (BET) for the endo and exo pathways indicate a one-step process with earlytransition states, which is compatible with the ELF topological examination of transition states.

2021-01

https://pubs.rsc.org/en/journals/journal/nj (Issue : 1) (Volume : 45)

The [3+2] cycloaddition (32CA) reactions of N-benzylcyclohexylnitrone 1 with methyl-3-butenoate 2 has been studied within molecular electron density theory (MEDT) at the B3LYP/6-311++G(d,p) level of theory. These zwitterionic type 32CA reactions occur through a one-step mechanism. The 32CA reactions undergo two pairs stereo- and regionisomeric reaction paths to form four different products, 3, 4, 5 and 6. The reaction paths are irreversible due to exothermic character of -18.5 and -12.4 kcal.mol-1. The 32CA reaction leading to the formation of cycloadduct 3 presents the lowest activation enthalpy than the other path due to a slighly increase in polar character evident from the global electron density transfer (GEDT) at the transition states and along the reaction path. The bonding evolution theory (BET) study suggests that these 32CA reactions occur through the coupling of pseudoradical centers and the formation of new CC and C-O covalent bonds has not been started in the transition states.

2019-10

WORLD JOURNAL OF PHARMACY AND PHARMACEUTICAL SCIENCES (Issue : 11) (Volume : 8)

Ibuprofen amino acid esters (2a-e) were synthesized by the reaction of ibuprofen (extraction from ibuprofen drug) with amino acid esters (glycine, phenylalanine, tyrosine, isoleucine, methionine) and they were converted to corresponding hydrazides (4a-e) by hydrazine hydrate. Hydrazones (5a-b) were synthesized by the reaction of hydrazide with p-nitrobenzaldehyde which cyclized to 1, 3, 4- oxadiazole 2, 5- disubstituted (7a-b) and phthalazine (6) by the reaction with lead oxide and hydrochloric acid, respectively. Ibuprofen amino acid amides (3a-d) were synthesized by passing ammonia gas through corresponding esters. The structures of the synthesized compounds were confirmed by physical and spectral methods. The antifungal activity of the compounds (Ibuprofen, 2e, 4c, 5a, 7a) against four types of fungi (A. Niger, A. tubingensis, A. foatiday, A. awamori) were studied and discussed.

2018-05

WORLD JOURNAL OF PHARMACY AND PHARMACEUTICAL SCIENCES (Issue : 6) (Volume : 7)

The present work describes the synthesis of new pyrrolidines and chalcone derivatives. Synthesis of chalcones (10-17) were acheved by condensation of diacetyl with substituted benzaldehyds in ethanolic sodium hydroxide (50%)(1: 2). The later compounds reacted with Schiff bases (1-8) to yield 1, 2-bis (2, 4, 5-tri (4-aryl) pyrrolidin-3-yl) ethane-1, 2-dione (20-27). The characterization of some resulting products were confirmed by physical properties, and spectral data UV-Visible, FT-IR, 1 H NMR, 13 C NMR.

2016-01

Swift Journal of Pharmacy and Pharmacology (Issue : 1) (Volume : 1)

Naproxen amino acid ester (2a-b) prepared by the reaction of naproxen with amino acid esters. Hydrazides (3a-b) were obtained by reaction of corresponding esters with hydrazine hydrate. These hydrazides were used to synthesize a series of five membered ring heterocyclic compounds, the hydrazides (3a-b) were converted to 1,3,4-oxadiazole-2-thione (4a-b) by their reaction with carbon disulfide in ethanolic potassium hydroxide. 2,5-Disubstituted 1,3,4-oxadiazole (6a-b) were obtained from the reaction of lead oxide with naproxen amino acid hydrazone (5a-b) where hydrazone prepared from the reaction of hydrazides (3a-b) with p-nitrobenzaldehyde. Mono substituted 1,3,4-oxadiazole (8a-b) were synthesized from the reaction of 2-formyl hydrazine (7a-b) with Phosphorous pentoxide. Finally, 4-amino 1,2,4-triazol-5-thiol (10a) was prepared from the reaction of dithiocarbazate salt with hydrazine hydrate. The structures of synthesized compounds were confirmed by physical and spectral means.

2016-01

Swift Journal of Pure and Applied Chemistry (Issue : 1) (Volume : 2)

A series of heterocyclic compounds tetrazole (3a-d) and 1,3-thiazolidin-4-one (4a-d) derivatives were synthesized by the reaction of Schiff base derivative (2a-d) with sodium azide, 2-mercptoactic acid respectively. The IR and 1HNMR spectral data of the synthesized compounds were also discussed.

2015-05

Journal of University of Zakho (Issue : 1) (Volume : 3)

The protected dipeptide esters (3a-e, 4a-l) is prepared by the reaction of compounds (1a-e, 2a-d) with dicyclohexylcarbodiamide (as coupling reagent) and amino acid esters .Thereafter hydrazides (5a-e, 6a-j) are obtained by the reaction of corresponding esters with hydrazine hydrate. Hydrazones (7a-e, 8a-e) are synthesized by the reaction of the above hydrazides with p-nitro benzaldehyde , which was cyclized to 2,5- disubstituted 1,3,4- oxadiazole (9a-e, 10a-e) through lead oxide and to phthalazines (13a-b) through hydrochloric acid. 1,3,4- oxadiazole -2- thione (11a-b, 12a-e) were prepared by the reaction of the corresponding hydrazides with carbon disulfide in alcoholic potassium hydroxide. Hydrazides were reacted with ammonium thiocyanate to afford thiosemicarbazide (14a-c) which were cyclized to 1,2,4- triazole -3- thione (15a-b) in sodium hydroxide medium. The structures of the synthesized compounds were confirmed by physical and spectral methods. The antibacterial activity of the prepared compounds (5d, 7a, 9e, 10d, 11a, 12e, 13a, 14b) against the gram +ve and –gram –ve Bactria (Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Proteus mirabilis) were studied and discussed.

2013-06

Science Journal of University of Zakho (Issue : 1) (Volume : 1)

2-hydroxy-1-napthaldehyde reacted with diaminophenol in absolute EtOH in a ratio 2: 1 to give new Schiff bases (H 2 L 1, H 2 L 2 and H 2 L 3). The obtained Schiff bases which were in tautomeric equilibrium (enol-imine OH… N, keto-amine O… HN forms) were used as ligands to coordinate Cu (II), Ni (II), and Co (II) leading complexes. The ligands and the complexes were characterized by physicochemical, elemental and spectroscopic analyses. The complexes exhibited 1: 1 metal to ligand coordination ratio (ML 1),(ML 2),(ML 3). Both Ligands and complexes were evaluated for antibacterial properties using disc diffusion method.. The complexes showed higher activity than the free ligands.

2008-03

Tikrit Journal of Pure Science (Issue : 1) (Volume : 13)

A number of hydrazone (2a-h) were synthesiszed from the reaction of protected amino acid hydrazide and substituted benzaldehyde. The obtained products then treated with amyl alcohol saturated with HCl gas to give a number of substituted phthalazine (3a-h). The structures of the synthesized compounds were confirmed by IR spectra methods.

2007-09

National Journal of Chemistry (Volume : 28)

Chloro-2-methyl thio-2-N-ethyl carbazato, 2N-acetyl tyrosyl hydrazido 4, 5-dioxo pyrano [3, 4-e]-1, 3-oxazine-4, 5-dione [2], 2, 7-di (N-ethyl carbazato) 4, 5-dioxo pyrano [3, 4-e]-1, 3-Oxazine-4, 5-dione [3] and, 7-chloro 2N-acetyl amino acid hydrazido, 2N-benzoyl amino acid Hydrazido-4, 5-dioxo pyrano [3, 4-e]-1, 3-oxazine 4, 5-dione [4] were synthesized by standard methods. The pyrano-1, 3-oxazine [1] was prepared from condensation of two moles of malonyl chloride with methyl or benzyl thiocyanate. Spectroscopic characteristics (IR, NMR) of the pyrano-1, 3-oxazine derivatives are presented and discussed.

2006-03

Iraqi National Journal Of Chemistry (Volume : 21)

Some heterocyclic compounds were prepared from the reaction of primary amine derivatives with imidate (which was prepared by the reaction of nitrile (1) with ethanol in presence of hydrogen chloride). Imidine was also prepared by the reaction of nitrile (1) with some primary amines in presence of aluminum chloride. The synthesized compounds were confirmed by IR spectra.

2005-04

Rafidain Journal of Science (Issue : 8) (Volume : 16)

Some new heterocyclic compounds of 1,2,4-oxadiazolidine-5-one derivatives [3a-m] were synthesized from the reaction of nitrone compounds with some isocyanates of amino acid esters in good yields. The reaction of nitrone compounds with cyclooctene and tetrahydrophthalic anhydride gave oxazolidine derivatives [4a-d]. The synthesized compounds were formed via 1,3-cycloaddition reaction of isocyanates and alkenes to nitrones. The I.R. spectral data of the synthesized compounds were also discussed.

2004-01

J. Educ. Sci. (Issue : 2) (Volume : 16)

N-(thiazloyl /benzothiazoyl) dipeptide ethyl ester were synthesized from the reaction of chloro acetic acid with 2-amino (thiazole/ benzothiazole).The products allowed to under goes reactions with thionyl chloride and then with some amino acid ester (glycine, tryrosine, cysteine, methionine, valine, phenyl alanine and lucine). The synthesized compounds have been characterized by I.R.and C.H.N. analyses.

2004-01

J. Educ. Sci. (Issue : 2) (Volume : 16)

N-(thiazloyl /benzothiazoyl) dipeptide ethyl ester were synthesized from the reaction of chloro acetic acid with 2-amino (thiazole/ benzothiazole).The products allowed to under goes reactions with thionyl chloride and then with some amino acid ester (glycine, tyrosine, cysteine, methionine, valine, phenyl alanine and leucine). The synthesized compounds have been characterized by I.R.and C.H.N. analyses.

2003-03

Teachers College Researchers journal (Issue : 1) (Volume : 1)

Some new amino acid derivatives were prepared from the reaction of amino acids esters (glycine, tyrosine and cystine) with 2-thioxo phthaloyl of the following amino acids (leucine, valine, glycine and alanine), The reaction products were tested against six types of bacteria. The results indicated that N-valyl-3-phthalimidine ethyl tyrosinate and N-anyl-3-phthalimidine ethyl cystinate showed remarkable activity against Pseudomonas araginosa. The synthesized compounds were characterized by using elemental analysis. IR spectral methods and their melting points.

2003-02

J. Educ. Sci. (Issue : 1) (Volume : 15)

A series of heterocyclic compounds, 1,2,4-triazole-5-one (4a-f) derivatives and substituted semicarbazides (3a-k) were prepared by condensation of N-acetyl or N- benzoyl amino acid hydrazides (1a-g) with isocyanate of some amino acid esters.(2a-e). The antimicrobial activity of some of the synthesized compounds especially compounds (3i and 4e) against six species of bacteria showed a significant activity against all types of the bacteria sutdieded. the products were identified on the bases of I.R. spectral data and elemental analysis

2003-01

Raf.Jour. Sci (Issue : 1) (Volume : 13)

A series of 1,3,4- Oxadiazole-2-one were synthesized by the reaction of amino acid hydrazides and dipeptides (valine, leucine, tyrosine, methionine, cysteine, and glycine) with carbone disulphide in alkaline medium gave 1,3,4-oxadiazol-2-one. The synthesized compounds were characterized by physical and spectral analysis.