Cristiano Raminelli

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

Chemoenzymatic resolution of β-azidophenylethanols by candida antarctica and their application for the synthesis of chiral benzotriazoles

The kinetic resolutions of (±)-β-azidophenylethanols were carried out using lipase from Candida antarctica, and enantiomerically enriched (R)-β-azidophenylethanols and their corresponding (S)-β-azidophenylethyl acetates were obtained in good enantiomeric excesses (up to > 99%). The enantiomerically enriched (R)-β-azidophenylethanols were subjected to cyclization reaction with 2-(trimethylsilyl)phenyl triflate and CsF producing chiral 1,2,3-benzotriazole compounds in good yields (75-86%) by a [3 + 2] cycloaddition, which involves the benzyne formation.

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%.

Straightforward and Clean Ultrasound-Promoted Synthesis of 2-(4,5-Dihydro-1H-pyrazol-1-yl)pyrimidines

A series of twelve novel 2-(pyrazol-1-yl)pyrimidine derivatives was easily obtained under ultrasonic conditions by the cyclocondensation reaction of 1-carboxamidino-pyrazoles with 4-methoxyvinyl-trifluoromethyl ketones using ethanol as an environment-friendly solvent in the presence of potassium hydroxide. Comparison of the ultrasound-promoted reaction with classical methodology shows that the former is faster and gives better yield. The products were isolated in excellent purity grades without purification by chromatography or recrystalization.

Palladium- and copper-catalyzed highly selective mono-coupling between 2,6-diiodoanisoles and terminal alkynes in the production of alkynylated anisoles as potential precursors of benzo[b]furans

The coupling reaction between 2,6-diiodoanisoles and terminal alkynes using Pd(PPh3)2Cl2 and CuI as catalysts and diisopropylamine as base in toluene at room temperature for 12 h produced selectively alkynylated 2-iodoanisoles, in good to excellent yields (52-95%), which are useful building blocks with potential application in the synthesis of functionalized benzo[b]furans.

Silylaryl triflates in the formation of arynes with application in the preparation of N,N-diarylamino acid derivatives

Through this work we are developing our research involving the formation of arynes from 2-(trimethylsilyl)aryl triflates, under relatively mild reaction conditions. Thus, esters of amino acids are being subjected to the reaction with 2-(trimethylsilyl)aryl triflates, using cesium fluoride in acetonitrile at 80 o C for 24 h, resulting in the formation of N,N-diarylamino acid derivatives, important chiral intermediates in the construction of peptides and drugs.

Synthesis of functionalized benzofurans by iodocyclization reaction of alkynylanisoles

Benzofurans are important synthetic building blocks present in a high number of biologically active natural products, pursuing several medicinal properties. In this context, there is an increasing interest in developing efficient syntheses for this class of compounds. Accordingly, we present in this work our preliminary results involving the iodocyclization reaction of 2-iodo-6-alkynylanisoles, employing molecular iodine under mild conditions, leading to the formation of highly functionalized benzofurans, potential precursors of pharmaceuticals and functional materials.