Unexpected Formation of Bis(hydrazinecarboximidamide) via Ultrasound Promoted Rearrangement of Epoxy Ketone

An efficient synthesis of aromatic pyrazoles via cyclocondensation of epoxy chalcones with hydrazine is reported. When aminoguanidine hydrochloride is the dinucleophilic specie the reaction leads to a mixture of amidino pyrazole and a minor amount (15%) of an interesting co-product identified as 2,2'-(1,3-diphenylpropane-1,2-diylidene)bis(hydrazinecarboximidamide) dihydrochloride by X-ray diffraction and NMR. A plausible mechanism for the co-product formation via rearrangement of the epoxy chalcone into 1,2-diketone followed by the condensation with aminoguanidine reaction is proposed. DOI: http://dx.doi.org/10.17807/orbital.v9i3.97

Palladium(II) complexes with thiosemicarbazones: syntheses, characterization and cytotoxicity against breast cancer cells and anti-mycobacterium tuberculosis activity

Three PdII complexes were prepared from N(4)-substituted thiosemicarbazones: [Pd(aptsc)(PPh3)](NO3)•H2O, 1, [Pd(apmtsc)(PPh3)](NO3), 2, and [Pd(apptsc)(PPh3)](NO3)•H2O, 3, where PPh3 = triphenylphosphine; Haptsc = 2-acetylpyridine-thiosemicarbazone; Hapmtsc = 2-acetylpyridine-N(4)-methyl-thiosemicarbazone and Happtsc = 2-acetylpyridine-N(4)-phenyl-thiosemicarbazone. All complexes were characterized by elemental analysis, IR, UV-Vis, 1H and 31P{1H} NMR spectroscopies, and had their crystalline structures determined by X-ray diffractometry from single crystals. The monoanionic thiosemicarbazonate ligands act in a tridentate mode, binding to the metal through the pyridine nitrogen, the azomethine nitrogen and the sulfur atoms. The cytotoxic activity against the breast cancer cell line MDA-MB231 and the anti-Mycobacterium tuberculosis H37Rv ATCC 27294 activity were evaluated for the compounds. All PdII complexes were highly active against the studied cell line, presenting similar values of IC50, around 5 µmol L-1, while the clinically applied antitumor agent cisplatin was inactive. The compounds show remarkable anti-M. tuberculosis activities, presenting MIC values comparable or better than some commercial anti-M tuberculosis drugs.FAPESPCAPESCNPqFINE

Palladium(II) complexes with thiosemicarbazones: syntheses, characterization and cytotoxicity against breast cancer cells and Anti-Mycobacterium tuberculosis activity

Três complexos de PdII com tiossemicarbazonas N(4)-substituídas foram preparados: [Pd(aptsc)(PPh3)](NO3) H2O, 1, [Pd(apmtsc)(PPh3)](NO3), 2, e [Pd(apptsc)(PPh3)](NO3) H2O, 3, sendo PPh3 = trifenilfosfina; Haptsc = 2-acetilpyridina-tiossemicarbazona; Hapmtsc = 2-acetilpiridina-N(4)-metil-tiossemicarbazona e Happtsc = 2-acetilpiridina-N(4)-fenil-tiossemicarbazona. Os complexos foram caracterizados por análise elementar, IR, UV-Vis, ¹H e 31P{¹H} NMR e tiveram suas estruturas cristalinas determinadas por difratometria de raios X em monocristal. Os ligantes tiossemicarbazonatos monoaniônicos atuam de modo tridentado, ligando-se ao metal pelos átomos de nitrogênio piridínico, nitrogênio azometínico e enxofre. A atividade citotóxica frente à linhagem de células tumorais MDA-MB231 (tumor de mama) e a atividade anti-Mycobacterium tuberculosis H37Rv ATCC 27294 dos compostos foram investigadas. Os complexos de PdII mostraram-se altamente ativos contra as células tumorais, com valores de IC50 em torno de 5 µmol L-1, enquanto o agente antitumoral em uso clínico cisplatina mostrou-se inativo. Os compostos apresentaram atividade anti-M. tuberculosis significante, com valores de CIM comparáveis ou melhores que aqueles referentes a alguns fármacos usados clinicamente contra tuberculose.Three PdII complexes were prepared from N(4)-substituted thiosemicarbazones: [Pd(aptsc)(PPh3)](NO3) H2O, 1, [Pd(apmtsc)(PPh3)](NO3), 2, and [Pd(apptsc)(PPh3)](NO3) H2O, 3, where PPh3 = triphenylphosphine; Haptsc = 2-acetylpyridine-thiosemicarbazone; Hapmtsc = 2-acetylpyridine-N(4)-methyl-thiosemicarbazone and Happtsc = 2-acetylpyridine-N(4)-phenyl-thiosemicarbazone. All complexes were characterized by elemental analysis, IR, UV-Vis, ¹H and 31P{¹H} NMR spectroscopies, and had their crystalline structures determined by X-ray diffractometry from single crystals. The monoanionic thiosemicarbazonate ligands act in a tridentate mode, binding to the metal through the pyridine nitrogen, the azomethine nitrogen and the sulfur atoms. The cytotoxic activity against the breast cancer cell line MDA-MB231 and the anti-Mycobacterium tuberculosis H37Rv ATCC 27294 activity were evaluated for the compounds. All PdII complexes were highly active against the studied cell line, presenting similar values of IC50, around 5 µmol L-1, while the clinically applied antitumor agent cisplatin was inactive. The compounds show remarkable anti-M. tuberculosis activities, presenting MIC values comparable or better than some commercial anti-M tuberculosis drugs

SeCl2-Mediated Approach Toward Indole-Containing Polysubstituted Selenophenes

A novel and efficient SeCl2-mediated chalcogenative cyclization strategy toward 3-selenophen-3-yl-1H-indoles from readily available and conveniently substituted propargyl indoles is described. It entails an unprecedented selenirenium-induced 1,2-indolyl shift prompted by the electrophilic addition of SeCl2 to the triple bond of the propargyl indole, followed by cyclization through the intermediacy of a 1-seleno-1,3-diene. The reaction takes place at room temperature and shows excellent selectivity, broad substrate scope, and wide functional group tolerance.Fil: Martins, Guilherme M.. Universidade Federal de Santa Maria; BrasilFil: Back, Davi Fernando. Universidade Federal de Santa Maria; BrasilFil: Kaufman, Teodoro Saul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Silveira, Claudio. Universidade Federal de Santa Maria; Brasi

Electrophilic Cyclization Involving Carbon–Selenium/Carbon–Halide Bond Formation: Synthesis of 3‑Substituted Selenophenes

The butylselanyl propargyl alcohols reacted with iodine to afford 3-iodoselenophenes. The change of nucleophile position from propargyl to homopropargyl was crucial for the aromatization and formation of selenophene rings. The experiments revealed that bromine and <i>N</i>-bromosuccinimide were not able to cyclize the butylselanyl propargyl alcohols; however, when the bromine source was copper­(II) bromide the corresponding 3-bromoselenophenes were obtained in good yields. In addition, the reaction of butylselanyl propargyl alcohols with diorganyl diselenides catalyzed by copper­(I) iodide gave the 3-(organoselanyl)­selenophenes. The reaction took place with aromatic rings substituted by either electron-donating or -withdrawing groups in the alkynes and propargyl positions. The steric effects of substituents were dominant in determining the yields, whereas electronic effects had only a minor influence. Furthermore, by monitoring the reaction by ¹H NMR, we were able to identify the key intermediate, which supported the elaboration of a proposed reaction mechanism. The 3-iodoselenophenes prepared allowed the synthesis of multifunctional selenophenes via application in metal-catalyzed coupling reactions, such as Sonogashira, Ullmann and Suzuki type reactions

Electrophilic Cyclization Involving Carbon–Selenium/Carbon–Halide Bond Formation: Synthesis of 3‑Substituted Selenophenes

The butylselanyl propargyl alcohols reacted with iodine to afford 3-iodoselenophenes. The change of nucleophile position from propargyl to homopropargyl was crucial for the aromatization and formation of selenophene rings. The experiments revealed that bromine and <i>N</i>-bromosuccinimide were not able to cyclize the butylselanyl propargyl alcohols; however, when the bromine source was copper­(II) bromide the corresponding 3-bromoselenophenes were obtained in good yields. In addition, the reaction of butylselanyl propargyl alcohols with diorganyl diselenides catalyzed by copper­(I) iodide gave the 3-(organoselanyl)­selenophenes. The reaction took place with aromatic rings substituted by either electron-donating or -withdrawing groups in the alkynes and propargyl positions. The steric effects of substituents were dominant in determining the yields, whereas electronic effects had only a minor influence. Furthermore, by monitoring the reaction by ¹H NMR, we were able to identify the key intermediate, which supported the elaboration of a proposed reaction mechanism. The 3-iodoselenophenes prepared allowed the synthesis of multifunctional selenophenes via application in metal-catalyzed coupling reactions, such as Sonogashira, Ullmann and Suzuki type reactions

Electrophilic Cyclization Involving Carbon–Selenium/Carbon–Halide Bond Formation: Synthesis of 3‑Substituted Selenophenes

The butylselanyl propargyl alcohols reacted with iodine to afford 3-iodoselenophenes. The change of nucleophile position from propargyl to homopropargyl was crucial for the aromatization and formation of selenophene rings. The experiments revealed that bromine and <i>N</i>-bromosuccinimide were not able to cyclize the butylselanyl propargyl alcohols; however, when the bromine source was copper­(II) bromide the corresponding 3-bromoselenophenes were obtained in good yields. In addition, the reaction of butylselanyl propargyl alcohols with diorganyl diselenides catalyzed by copper­(I) iodide gave the 3-(organoselanyl)­selenophenes. The reaction took place with aromatic rings substituted by either electron-donating or -withdrawing groups in the alkynes and propargyl positions. The steric effects of substituents were dominant in determining the yields, whereas electronic effects had only a minor influence. Furthermore, by monitoring the reaction by ¹H NMR, we were able to identify the key intermediate, which supported the elaboration of a proposed reaction mechanism. The 3-iodoselenophenes prepared allowed the synthesis of multifunctional selenophenes via application in metal-catalyzed coupling reactions, such as Sonogashira, Ullmann and Suzuki type reactions

Electrophilic Cyclization Involving Carbon–Selenium/Carbon–Halide Bond Formation: Synthesis of 3‑Substituted Selenophenes

The butylselanyl propargyl alcohols reacted with iodine to afford 3-iodoselenophenes. The change of nucleophile position from propargyl to homopropargyl was crucial for the aromatization and formation of selenophene rings. The experiments revealed that bromine and <i>N</i>-bromosuccinimide were not able to cyclize the butylselanyl propargyl alcohols; however, when the bromine source was copper­(II) bromide the corresponding 3-bromoselenophenes were obtained in good yields. In addition, the reaction of butylselanyl propargyl alcohols with diorganyl diselenides catalyzed by copper­(I) iodide gave the 3-(organoselanyl)­selenophenes. The reaction took place with aromatic rings substituted by either electron-donating or -withdrawing groups in the alkynes and propargyl positions. The steric effects of substituents were dominant in determining the yields, whereas electronic effects had only a minor influence. Furthermore, by monitoring the reaction by ¹H NMR, we were able to identify the key intermediate, which supported the elaboration of a proposed reaction mechanism. The 3-iodoselenophenes prepared allowed the synthesis of multifunctional selenophenes via application in metal-catalyzed coupling reactions, such as Sonogashira, Ullmann and Suzuki type reactions

Electrophilic Cyclization Involving Carbon–Selenium/Carbon–Halide Bond Formation: Synthesis of 3‑Substituted Selenophenes

The butylselanyl propargyl alcohols reacted with iodine to afford 3-iodoselenophenes. The change of nucleophile position from propargyl to homopropargyl was crucial for the aromatization and formation of selenophene rings. The experiments revealed that bromine and <i>N</i>-bromosuccinimide were not able to cyclize the butylselanyl propargyl alcohols; however, when the bromine source was copper­(II) bromide the corresponding 3-bromoselenophenes were obtained in good yields. In addition, the reaction of butylselanyl propargyl alcohols with diorganyl diselenides catalyzed by copper­(I) iodide gave the 3-(organoselanyl)­selenophenes. The reaction took place with aromatic rings substituted by either electron-donating or -withdrawing groups in the alkynes and propargyl positions. The steric effects of substituents were dominant in determining the yields, whereas electronic effects had only a minor influence. Furthermore, by monitoring the reaction by ¹H NMR, we were able to identify the key intermediate, which supported the elaboration of a proposed reaction mechanism. The 3-iodoselenophenes prepared allowed the synthesis of multifunctional selenophenes via application in metal-catalyzed coupling reactions, such as Sonogashira, Ullmann and Suzuki type reactions

2,20-Dihydroxy-N,N0-(ethane-1,2-diyl)- dibenzamide

The asymmetric unit of the title compound, C16H16N2O4, contains one half-molecule, the whole molecule being generated by an inversion center located at the mid-point of the C-C bond of the central ethane group. An intramolecular O-H...O hydrogen bond forms an S(6) ring motif. In the crystal, molecules are connected via N-H...O hydrogen bonds, generating infinite chains along [1-10]