Rodrigo Abonia

Synthesis of novel pyrazolic analogues of chalcones and their 3-aryl-4-(3-aryl-4,5-dihydro-1H-pyrazol-5-yl)-1-phenyl-1H-pyrazole derivatives as potential antitumor agents

Novel (E)-1-aryl-3-(3-aryl-1-phenyl-1H-pyrazol-4-yl)prop-2-en-1-ones 5/6 (pyrazolic chalcones) were synthesized from a Claisen-Schmidt reaction of 3-aryl-1-phenylpyrazol-4-carboxaldehydes 4 with several acetophenone derivatives 1. Subsequently, the microwave-assisted cyclocondensation reaction of chalcones 5/6 with hydrazine afforded the new racemic 3-aryl-4-(3-aryl-4,5-dihydro-1H-pyrazol-5-yl)-1-phenyl-1H-pyrazoles 7 or their N-acetyl derivatives 8 and 9 when reactions where carried out in DMF or acetic acid, respectively. Several of these compounds were screened by the US National Cancer Institute (NCI) for their ability to inhibit 60 different human tumor cell lines, where 5c and 9g showed remarkable activity mainly against leukemia (K-562 and SR), renal cancer (UO-31) and non-small cell lung cancer (HOP-92) cell lines, with the most important GI50 values ranging from 0.04 to 11.4 microM, from the in vitro assays.

Regioselective synthesis of 4,7,8,9-tetrahydro-2H-pyrazolo[3,4-b]quinolin-5(6H)-ones. Mechanism and structural analysis

Abstract Reactions of 5-amino-3-methyl-1H-pyrazole with dimedone and aldehydes afford regioselectivelly tricyclic linear 3,7,7-trimethyl-4,7,8,9-tetrahydro-2H-pyrazolo[3,4-b]quinolin-5(6H)-ones in good yields. Several aspects on this regioselective reaction, such as the reaction mechanism and structural studies of the predominant tautomeric form, are treated.

A regiospecific three-component one-step cyclocondensation to 6-cyano-5,8-dihydropyrido[2,3-d]pyrimidin-4(3H)-ones. Using microwaves under solvent-free conditions

In a solvent-free system, regiospecific three-component one-step cyclocondensation to dihydropyrido[2,3-d]pyrimidin-4(3H)-ones 4 starting from readily available aminopyrimidin-4(3H)-ones 1, benzoylacetonitrile 2 and benzaldehydes 3 by microwave radiation was carried out. This rapid method produces pure products in high yields (70–75%).

Synthesis of novel quinoline-2-one based chalcones of potential anti-tumor activity.

Novel quinoline-2-one based chalcones were synthesized from a Claisen-Schmidt condensation by using the couple KOH/1,4-dioxane as reaction medium. A relatively stable aldol was isolated and identified as the intermediate species in the formation of the target chalcones. Nine of the obtained compounds were in vitro screened by the US National Cancer Institute (NCI) for their ability to inhibit 60 different human tumor cell lines. Products 16c, 16d, 16h and 27 exhibited the highest activity, being compound 27 the most active, displaying remarkable activity against 50 human tumor cell lines, thirteen of them with GI(50) values ≤1.0 μM, being the HCT-116 (Colon, GI(50) = 0.131 μM) and LOX IMVI (Melanoma, GI(50) = 0.134 μM) the most sensitive strains. Compound 27 was referred to in vivo acute toxicity and hollow fiber assay by the Biological Evaluation Committee of the NCI. The acute toxicity study indicated that compound 27 was well tolerated intraperitoneally (150 mg/kg/dose) by athymic nude mice. This compound may possibly be used as lead compound for developing new anticancer agents.

Synthesis of novel 1,2,5-trisubstituted benzimidazoles as potential antitumor agents

Novel methyl 1-(5-tert-butyl-1H-pyrazol-3-yl)-2-(aryl)-1H-benzo[d]imidazole-5-carboxylates 11 were synthesized by following a four-step strategy involving a nucleophilic aromatic displacement (S(N)Ar) and a solvent free approach as key steps for the formation of the desired products. Structure of intermediates and products were confirmed by X-ray diffraction as well as the tautomeric rearrangement suffered by the pyrazole moiety during the curse of the final cyclization process. Several of the obtained compounds were screened by the US National Cancer Institute (NCI) for their ability to inhibit 60 different human tumor cell lines. Products 11b and 11n exhibited the highest activity against a range of cancer cell lines with remarkable values in panels of Non-Small Cell Lung Cancer, Melanoma and Leukemia, with GI(50) range of 1.15-7.33 μM and 0.167-7.59 μM, respectively, and suitable LC(50) with values greater than 100 μM.

A novel product from the reaction of 6-aminopyrimidines and 3-formylchromone

Abstract The reaction of 6-aminopyrimidines 4 with 3-formylchromone under microwave irradiation in dry media and classical heating in absolute ethanol afforded in all cases the unexpected 6-hydroxy-6,9-dihydrobenzopyranopyrido[2,3- d ]pyrimidin-8-ones 6a – e (alternatively named, 6-hydroxy-6,9-dihydro-5-oxa-9,11,12-triazabenzo[ a ]anthracen-8-ones). The structure of the final compounds was determined on the basis of NMR measurements, especially by 1 H, 1 H- and 1 H, 13 C COSY, DEPT, HSQC, HMBC and NOESY.

Microwave induced synthesis of novel 8,9-dihydro-7H-pyrimido[4,5-b][1,4]diazepines as potential antitumor agents

A series of new racemic 4-amino-6-aryl-8-(1,3-benzodioxol-5-yl)-8,9-dihydro-7H-pyrimido[4,5-b][1,4]diazepines 4a-f and 4-amino-8-aryl-6-(1,3-benzodioxol-5-yl)-8,9-dihydro-7H-pyrimido[4,5-b][1,4]diazepines 5a-f were obtained regioselectively from the reaction of 4,5,6-triaminopyrimidine 1 with 1equiv of methylenedioxychalcones 2a-f and 3a-f, under microwave irradiation. Detailed NMR measurements confirm the high regioselectivity of this reaction. These compounds have been evaluated in the US National Cancer Institute (NCI) for their ability to inhibit approximately 60 different human tumor cell lines, where 4e, 5a and 5b presented remarkable activity against 47, 11 and 37 cancer cell lines, respectively, with the most important GI50 values ranging from 0.068 to 0.35 microM, in vitro assay.

Synthesis of new indeno[1,2-e]pyrimido[4,5-b][1,4]diazepine-5,11-diones as potential antitumor agents

Novel racemic indeno[1,2-e]pyrimido[4,5-b][1,4]diazepine-5,11-diones 3-29 were obtained regioselectivily from the reaction of 5,6-diamino-3,4-dihydropyrimidin-4-ones 1 and 2-arylideneindandiones 2 as reagents. These compounds have been evaluated at the US National Cancer Institute (NCI) for their ability to inhibit approximately 60 different human tumor cell lines, where 5 and 6 presented remarkable activity against 57 and 48 cancer cell lines, respectively, with the most important GI(50) values ranging from 0.49 to 1.46 microM, in vitro assay.

The Aryne aza-Diels-Alder Reaction: Flexible Syntheses of Isoquinolines.

Two cascade reactions have been developed for the time-efficient preparation of a variety of functionalized aromatic heterocyclic products exhibiting an isoquinoline core. The approach is based on the normal electron-demand [4 + 2] aza-Diels-Alder cycloaddition of electron-rich N-aryl imines with arynes. Using this strategy, an expeditious total synthesis of the naturally occurring benzo[c]phenanthridine alkaloid nornitidine was achieved.

Chemical and spectroscopic characterization of a vegetable oil used as dielectric coolant in distribution transformers

In this work, a complete UV-Vis, IR and (1H, 13C and DEPT) NMR spectroscopic analysis was performed for a FR3® vegetable oil sample used as dielectric coolant in an experimental distribution transformer. The same spectroscopic analysis was performed for three used FR3® oil samples (i.e., 4 months in use, 8 months in use and 7 years in use), removed from several operating distribution transformers. Comparison of the data indicated that no significant spectroscopic changes, and hence, no structural changes occurred to the oils by the use. Chemical transformations like catalytic hydrogenation (hardening) and hydrolysis were performed to the FR3® oil sample and the obtained products were analyzed by spectroscopic methods in order to collect further structural information about the FR3® oil. Accelerated aging tests in laboratory were also performed for three FR3® oil samples affording interesting information about the structure of the degradation products. These findings would be valuable to search for a spectroscopy-based technique for monitoring the life-time and performance of this insulating vegetable oil.