No abstract

The first synthesis of meso-fused carbaporphyrin via a premodification method was accomplished by substituting two pyrrole moieties and one meso-carbon with 2-(naphthalen-1-yl)thiophene. The obtained global π-conjugation pathway of the macrocycle noticeably disturbs the 10π local aromaticity of naphthalene, and its aromatic nature was supported by NMR spectroscopy together with nucleus-independent chemical shift, anisotropy of the induced current density, and harmonic oscillator stabilization energy calculations. In addition, the meso-fused carbaporphyrin also allowed the formation of a square planar Pd(II) complex.

An anthracene-containing meso-fused carbaporphyrin, which has extended π-conjugation pathways as compared to the corresponding naphthalene-containing carbaporphyrin, has been synthesized. The weak global aromaticity of the anthriporphyrin also allowed its use as the diene for a Diels-Alder reaction with dimethyl acetylenedicarboxylate (DMAD). The resulting phlorin contains an interesting bicyclic structure. Moreover, to the best of our knowledge, this phlorin is the first Diels-Alder adduct of a diene forming part of the global π-conjugation pathway of an aromatic porphyrinoid.

Uma nova série de 4-amino-5-aril-3H-1,2,4-triazol-3-tionas, tendo vários grupos metoxibenzila e metoxifenila, foi sintetizada através de refluxo de sais de hidrazina carboditioato de potássio em solução aquosa diluída de hidrato de hidrazina. Estes sais foram formados pela reação de hidrazinas ácidas e dissulfeto de carbono em solução de hidróxido de potássio metanólico a 0-5 °C. 4-Amino-5-aril-3H-1,2,4-triazol-3-tionas foram condensadas com diferentes ácidos aromáticos substituídos para produzir 1,2,4-triazol[3,4-b]1,3,4-tiodiazols 3,6-disubstituídos. As estruturas dos compostos sintetizados foram caracterizadas pelas espectroscopias no infravermelho (IR) e ressonância magnética nuclear (NMR) de 1 H e 13 C, análise elementar e espectrometria de massa (MS). Todos os compostos sintetizados foram examinados com relação as suas atividades de inibição de urease, antioxidante e antibacteriana. Alguns compostos mostraram excelente atividade de inibição de urease, mais do que a droga padrão. Outros compostos apresentaram potente atividade antioxidante. Todos os compostos mostraram atividades antibacterianas significativas em comparação com a droga padrão. A new series of 4-amino-5-aryl-3H-1,2,4-triazole-3-thiones, bearing various methoxybenzyl-and methoxyphenethyl groups, was synthesized by refluxing potassium hydrazinecarbodithioate salts in dilute aqueous solution of hydrazine hydrate. These salts were formed by the reaction of acid hydrazides and carbon disulfide in methanolic potassium hydroxide solution at 0-5 °C. 4-Amino-5-aryl-3H-1,2,4-triazole-3-thiones were condensed with different substituted aromatic acids to yield 3,6-disubstituted-1,2,4-triazolo[3,4-b]1,3,4-thiadiazoles. The structures of the synthesized compounds were characterized by infrared (IR), 1 H and 13 C nuclear magnetic resonance (NMR), elemental analysis and mass spectrometric (MS) studies. All the synthesized compounds were screened for their urease inhibition, antioxidant and antibacterial activities. Some compounds showed excellent urease inhibition activity, more than the standard drug. Others exhibited potent antioxidant activity. All the compounds showed significant antibacterial activities as compared to the standard drug.

The first fully connected aromatic carbaporphyrin dimer (6) and its bis-Pd complex (6-Pd 2 ) that bear a rigid naphthalene motif as an internal strap were synthesized. These dimers consisted of two aromatic carbaporphyrins that shared a naphthalene motif. The π-electron conjugation of the obtained macrocycles was proposed to have two separated local 22 π-electron pathways and a 34 π-electron pathway. Their weak aromaticity was fully supported by 1H NMR spectroscopy, NICS values, ACID calculations, and ICSS plots.

Allyliporphyrin is a carbaporphyrin that has replaced one pyrrole with an allyl group. Dynamic behavior (bond rotation) was observed by variable temperature H NMR and 2D-NOESY NMR spectroscopy and theoretically examined by DFT calculations. These studies revealed that well-defined bond rotation was first observed in the limited space of the carbaporphyrin from 2 through cis-2 and the calculated rotational barrier was low enough, with the relative energy level of cis-2 only 0.65 kcal mol higher than 2. The synthesized allyliporphyrin (2) is a strongly aromatic macrocycle as indicated by the chemical shifts of its inner NH and CH signals. However, its palladium complex displayed reduced aromaticity due to the tilted thiophene of Pd-2.

The first aromatic benzicorrole termed naphthicorrole was synthesized with a carbon donor containing more than six members. Its oxidized (enedione-embedded) porphyrinoid was also obtained using different meso-aryl substitutions under sequential oxidation conditions. The resulting enedione motif of the nonaromatic porphyrinoid was regioselective to the C2 position for S or N nucleophiles. Thus, the oxidized porphyrinoid was tested as a built-in linker for biomolecules. The progress of the reaction was visually monitored due to their different conjugation pathways.

A new series of 4,5-disubstituted-2,4-dihydro-3H-1,2,4-triazole-3-thiones (6a–s) and 2,5-disubstituted-1,3,4-thiadiazoles (7a–h) was synthesized by intramolecular dehydrocyclization of various 1,4-disubstituted thiosemicarbazide derivatives (5a–s) by refluxing in 4 N aqueous sodium hydroxide and by overnight stirring with polyphosphoric acid, respectively. The structures of these compounds were characterized by IR, 1H and 13C NMR, elemental analysis and mass spectroscopic studies. All the synthesized compounds were screened for their acetylcholinesterase and alkaline phosphatase inhibition studies. Most of the tested compounds showed promising activities, amongst them (6k) and (6q) showed excellent acetylcholinesterase inhibitory activity with IC50 0.241 ± 0.012 and 0.260 ± 0.013 µM, respectively, as compared with those of standard drug whereas the compound (6p), with IC50 0.044 ± 0.001 µM, was found to be the most potent inhibitor of alkaline phosphatase.