Gleison A. Casagrande

Total Syntheses of Aporphine Alkaloids via Benzyne Chemistry: An Approach to the Formation of Aporphine Cores.

Total syntheses of lysicamine, (±)-nuciferine, (±)-nornuciferine, (±)-zanthoxyphylline iodide, (±)-O-methylisothebaine, and (±)-trimethoxynoraporphine were accomplished by an approach that involves the formation of aporphine cores through reactions between an isoquinoline derivative and silylaryl triflates promoted by CsF. Unprecedented formations of aporphine cores proceeded in good yields presumably through [4 + 2] cycloaddition reactions followed by hydrogen migrations.

Oxidative Stability of Baru (Dipteryx alata Vogel) Oil Monitored by Fluorescence and Absorption Spectroscopy

Baru (Dipteryx alata Vogel) is a native fruit of the Brazilian savanna that provides a nutritive oil, which also has medicinal properties. Baru fruits were collected in central-western Brazil, and the oil was obtained by pressing the seeds. The Baru oil was heated at 110°C for 24 h, and its oxidative stability was investigated by using fluorescence and absorption spectroscopy. The data showed that both absorption and fluorescence were able to precisely monitor the oil degradation induced by the thermooxidative process. The results revealed a rapid growth of the primary compounds generation in the first 16 hours of degradation. Significant amounts of secondary compounds began to be generated after 14 hours.

Synthesis and Characterization of Mesoporous Nb2O5 and Its Application for Photocatalytic Degradation of the Herbicide Methylviologen

This article reports the characterization of mesoporous Nb2O5 synthesized by the sol-gel method for application in photocatalysis. The emerging contaminant methylviologen was employed for photocatalytic tests. Parameters inherent to the synthesis process, such as stirring rate, aging temperature, and calcination temperature, were employed for a range of values to improve the synthetic route. The powders obtained were characterized by thermogravimetric analysis, X-ray diffraction, scanning and transmission electron microscopy, specific surface area, infrared spectroscopy, energy-dispersive spectroscopy, and diffuse reflectance spectroscopy. In samples calcined at 450 °C, a mixture of amorphous and hexagonal phases was observed, with a predominance of the former, while in samples calcined at 650 °C the orthorhombic phase predominated. Samples calcined at 450 °C exhibited larger specific surface areas. Mesoporous structures were confirmed for samples T8035M450 and T8045mi450, which displayed higher photoactivity, with roughly 90% removal of methylviologen.

Water as an Eco-friendly Solvent for Iodination Reactions of Aromatic and Heteroaromatic Compounds

In this review article we have gathered relatively recent publications involving modern methodologies for iodi- nation reactions of aromatic and heteroaromatic compounds using pure water or mixtures containing water as environ- mentally friendly media.

Ultrasound-Promoted Environmentally Friendly Synthesis of 5-(3,3,3-Trifluoro-2-oxopropylidene)pyrrolidin-2-ones

Abstract A facile, one-pot, ultrasound-promoted synthesis of N-substituted 5-(3,3,3-trifluoro-2-oxopropylidene)pyrrolidin-2-ones from methyl 7,7,7-trifluoro-4-methoxy-6-oxohept-4-enoate and a wide range of primary alkyl(aryl)amines using ethanol as a green solvent and employing triethylamine as a base is described. GRAPHICAL ABSTRACT

Ultrasound-Promoted Rapid and Efficient Iodination of Aromatic and Heteroaromatic Compounds in the Presence of Iodine and Hydrogen Peroxide in Water

Abstract A rapid and efficient ultrasound-promoted protocol for iodination of aromatic and heteroaromatic compounds, using molecular iodine in the presence of aqueous hydrogen peroxide in water without any cosolvent, has produced versatile iodinated organic molecules with potential application in organic synthesis and medicine in short reaction times and good to excellent yields. GRAPHICAL ABSTRACT

Ultrasound-Promoted Synthesis of 3-(Thiophen-2-yl)-4,5-dihydro-1H-pyrazole-1- carboximidamides and Anticancer Activity Evaluation in Leukemia Cell Lines

3-(Thiophen-2-yl)-4,5-dihydro-1H-pyrazole-1-carboximidamides were efficiently prepared through a cyclocondensation of thiophenylchalcones with aminoguanidine hydrochloride under ultrasonic conditions in the presence of KOH and ethanol as a green solvent in short reaction times (15-35 min) and good yields (62-95%). All compounds produced were evaluated against the human Jurkat and RS4;11 acute lymphoblastic leukemia cell lines of T- and B-cell origin, respectively, and the K562 myelogenous leukemia cell line. Six compounds presented half maximal inhibitory concentration (IC50) values around 15 µmol L-1 and five compounds presented IC50 values around 40 µmol L-1 for at least one of the three cell lines analyzed. One compound was not significantly cytotoxic, presenting IC50 value > 100 µmol L-1.

Fluorescence analysis of iodinated acetophenone derivatives

In the present paper the synthesis and optical characterization of iodinated acetophenone, 4-hydroxy-3-iodoacetophenone and 4-hydroxy-3,5-diiodoacetophenone obtained from 4-hydroxyacetophenone, were carried out. The optical features of iodinated molecules were determined by performing the UV-Vis absorption, fluorescence and thermal lens spectroscopies. The results showed that the optical properties of the 4-hydroxyacetophenone is altered when the iodine atom is inserted, as substituent, in the aromatic ring. Although it was determined that the optical feature was changed when one iodine atom was inserted in the aromatic ring (4-hydroxy-3-iodoacetophenone), the results revealed that emission behavior was strongly altered when two iodine atoms (4-hydroxy-3,5-diiodoacetophenone) were acting as substituents: the fluorescence quantum efficiency increases approximately 60%.

Cu(I)-phosphine complex: An efficient catalyst for synthesis of 3-indole derivatives through one-pot MCR under mild conditions

ABSTRACT An efficient copper (I) halotriphenylphosphine catalyzed one-pot multicomponent reaction (MCR) of 3-substituted indole derivatives has been developed using a variety of aldehydes (aromatic, aliphatic, and heteroaromatic), indole, and active methylene substrates such as malononitrile and ethyl 2-cyano acetate. This reaction proceeds smoothly and obtained good to excellent yields (68–93%) using water as green solvent under ambient conditions. The obtained products were confirmed by 1H, 13C NMR, and mass spectroscopy techniques. The one-pot MCR occurs through formation of Knoevenagel adducts then followed by Michael addition of indole. GRAPHICAL ABSTRACT

Synthesis of Diiodo-Functionalized Benzo[b] furans via Electrophilic Iodocyclization

Heterocyclic aromatic compounds constitute a class of substances with a considerable diversity of pharmacological properties. Accordingly, natural and synthetic heteroaromatic compounds have been employed as drugs. Focusing on benzo[b]furans (1), we came across an important subclass of heterocyclic aromatic compounds, which comprises various biological activities, such as anticancer, antiviral, anti-inflammatory, and immunosuppressive. In this sense, we present the structures of the benzo[b]furans obovaten (2), a natural product with pronounced antitumor activity, and amiodarone (3), a commercial antiarrhythmic drug (Figure 1). A number of approaches have been developed towards the efficient construction of benzo[b]furan scaffolds. Among them we highlight the metal-catalyzed cross-coupling/ cyclization reactions and the electrophilic cyclization reactions employing alkynylanisoles. The latter approach can be illustrated by the iodocyclization reaction developed by Larock and co-workers. Nevertheless, in the course of our research activities aiming to the synthesis of diiodo-functionalized compounds, for application in selective cross-coupling reactions, we observed that diiodo-functionalized benzo[b]furans could not be achieved through the reaction between alkynylated 2-iodoanysoles and molecular iodine, using the Larock’s conditions for the preparation of iodinated benzo[b]furans. In this context, we focused on development of a novel methodology to obtain diiodo-functionalized benzo[b]furans via electrophilic iodocyclization reaction, employing alkynylated 2-iodoanysoles and molecular iodine.