Ivan A Pinto CC - Academia.edu (original) (raw)

Papers by Ivan A Pinto CC

Em Manutencao, May 8, 2008

Um novo logo corporativo da Unilever identificara a empresa como responsavel por todos os seus pr... more Um novo logo corporativo da Unilever identificara a empresa como responsavel por todos os seus produtos, nas embalagens de todas as suas marcas, no mundo inteiro.

Revista Psicologia Teoria E Pratica, Sep 16, 2013

Sistema de avaliação: às cegas por pares (double blind review). Universidade Presbiteriana Macken... more Sistema de avaliação: às cegas por pares (double blind review). Universidade Presbiteriana Mackenzie.

Comprehensive Organic Synthesis, 1991

The synthetic versatility of α,β-unsaturated carbonyl compounds has resulted in the development o... more The synthetic versatility of α,β-unsaturated carbonyl compounds has resulted in the development of a wide variety of methods for their synthesis. Many such procedures rely on the construction of the basic carbon framework from simpler fragments, and are typified by reactions of the Wittig, Knoevenagel, aldol and Reformatsky type.1 To be able to introduce regioselective unsaturation into a previously established carbon skeleton is, however, an additional tool in the chemist’s armamentarium. In this review we have attempted to bring together the main literature relating to dehydrogenation methodology. No attempt has been made to include similar reactions that would generate alkynes or reactions that would result in the formation of carbon atoms doubly bonded to heteroatoms. Several of the intermediates described, and especially those involving α-selenenyl or α-thio moieties, offer the opportunity for further elaboration prior to elimination, since such species are able to stabilize adjacent carbanions.2–4 The synthetic applications arising from such intermediates are left to the ingenuity of the reader.

Journal of the Chemical Society, Perkin Transactions 1, 1992

Journal of the Chemical Society, Perkin Transactions 1, 1991

The syntheses of analogues of the novel smooth muscle relaxant cromakalim, in which the C-2 methy... more The syntheses of analogues of the novel smooth muscle relaxant cromakalim, in which the C-2 methyl groups have been successively replaced by hydrogen, are described and the relative stereochemistry of the two corresponding, isomeric monomethyl compounds, ...

Journal of the Chemical Society, Chemical Communications, 1989

Reaction of 4-bromo-6-cyano-3,4-dihydro-2,2-dimethyl-3,3-ethylenedioxy-2H-1-benzopyran (2) with s... more Reaction of 4-bromo-6-cyano-3,4-dihydro-2,2-dimethyl-3,3-ethylenedioxy-2H-1-benzopyran (2) with secondary amide anions provides C-5 substituted products in moderate yields.

Tetrahedron Letters, 1992

The reaction of electron &jicient pyrroles and pyrazoles with tram 3-bromo-&cyano-3,4-dihydro-2,2... more The reaction of electron &jicient pyrroles and pyrazoles with tram 3-bromo-&cyano-3,4-dihydro-2,2-dimethyl-ZH-I-benzopyrun-4-al under basic conditions results in the formation of 2-isopropylbenzofurans by a mechanism which appears to be dependent on the rate of the competitive dehydration reaction ieading to rhe corresponding benzopyrans.

Tetrahedron Letters, 1989

Tetrahedron Letters, 2000

5-Alkoxythiophenes have been prepared by an extension of the Gewald thiophene synthesis and a nov... more 5-Alkoxythiophenes have been prepared by an extension of the Gewald thiophene synthesis and a novel four component condensation reaction uncovered by which 5-aminothiophenes have been prepared.

Organic Letters, 2004

Method A-Acrylamide formation. Triethylamine (2 equiv.), amine (2.2 equiv.) and DMAP (0.1 equiv.)... more Method A-Acrylamide formation. Triethylamine (2 equiv.), amine (2.2 equiv.) and DMAP (0.1 equiv.) in CH 2 Cl 2 were stirred at 0 ºC under a nitrogen atmosphere for 15 min. A solution of the acryloyl chloride (1 equiv.) in CH 2 Cl 2 was added dropwise at 0 ºC over 10 min and the solution stirred at room temperature for 14 h. 2 M HCl was added and the layers were separated. The organic layer was washed with 2M HCl and water, dried (MgSO 4) and concentrated under reduced pressure to afford the crude product. Method B-Pyrrole formation using TosMIC. 1 Acrylamide (1 equiv.) and tosylmethylisocyanide (1 equiv.) in DMSO and diethyl ether (1:1.3) were added dropwise to a stirred suspension of sodium hydride (1.3 equiv.) in diethyl ether at 0 ˚C, under a nitrogen atmosphere. The reaction mixture was stirred at room temperature for 4 h, and quenched with water and 1 M potassium hydroxide solution. The mixture was extracted with diethyl ether, combined organic layers were washed with water, dried (MgSO 4) and evaporated under reduced pressure to yield the crude product. Method C-DEB protection. 2 A solution of the amide (1 equiv.) in THF was added dropwise to a suspension of sodium hydride (3 equiv. of 60 % suspension) in THF at 0 °C, under a nitrogen atmosphere. The mixture was stirred at room temperature for 1 h then cooled to 0 °C. A solution of DEB-Cl 3 (1.35 equiv.) in THF was added dropwise and the reaction stirred at room temperature for 16 h then quenched with ammonium chloride. Water was added and the organic phase separated. The aqueous layer was extracted with diethyl ether and the combined organic extracts washed with water then brine, dried (MgSO 4), and the solvent removed under reduced pressure to yield the crude product. Method D-Cyclisation using LDA. 4 n-Butyllithium (3 equiv.; 2.5 M solution in hexane) was added dropwise to a stirred solution of diisopropylamine (3 equiv.) in THF at 0 °C, under a nitrogen atmosphere. The LDA solution was allowed to stir at this temperature for 20 minutes, and a solution of the amide in THF was added via cannula at 0 °C. The mixture was stirred at 0 °C for 3 hours before quenching with the electrophile (6 equiv.). Water was added and the organic phase separated. The aqueous layer was extracted with diethyl ether and the combined organic extracts washed with water then brine, dried (MgSO 4), and the solvent removed under reduced pressure to yield the crude product. Method E-Cyclisation using chiral base (R)-N-isopropyl-_-methylbenzylamine. 5 n-BuLi (0.96 mL of a 2.5 M solution in hexanes, 2.36 mmol, 6.0 equiv.) was added dropwise to a stirred solution of chiral base (0.23 g, 1.18 mmol, 3.0 equiv.) in THF (2 mL) at-78 ºC, under a nitrogen atmosphere, and the mixture allowed to warm to room temperature for 15 min-until the salt dissolved. The solution was cooled to-78 ºC and the amide (0.15 g, 0.39 mmol, 1 equiv.) in THF (2 mL) added dropwise, gradually allowed to warm to 0 ºC over 5 h then quenched with NH 4 Cl (2.5 mL), after 10 min water (5 mL) was added and the mixture extracted with Et 2 O (4 x 5 mL). Combined organics were washed with water (5 mL), dried over MgSO 4 , filtered and evaporated under reduced pressure to yield the crude product. Method F-Allylation. Amide (1 equiv.) in DMF was added dropwise to a suspension of sodium hydride (1.5 equiv.) in DMF at 0 ºC under a nitrogen atmosphere. The solution was stirred at room temperature for 30 min and a solution of the allyl bromide (1.2 equiv.) in DMF added dropwise at 0 ºC. The solution was stirred at room temperature for 1 h and quenched with water. The mixture was extracted with EtOAc and combined organic fractions washed with water, dried (MgSO 4) and concentrated under reduced pressure to afford the crude product. N-Benzyl-N-tert-butyl-acrylamide (2a) N O N-tert-butylbenzylamine (6 mL, 32.6 mmol, 2.2 equiv.) and acryloyl chloride (1.2 mL, 14.8 mmol, 1 equiv.) were treated according to Method A to afford the title compound (3.2 g, 99 %) as needles;

Journal of Medicinal Chemistry, 1990

A series of 4-amido-3,4-dihydro-2H-1-benzopyran-3-ols and 4-amido-2H-1-benzopyrans related to the... more A series of 4-amido-3,4-dihydro-2H-1-benzopyran-3-ols and 4-amido-2H-1-benzopyrans related to the potassium channel activator cromakalim have been prepared and evaluated for their relaxant activity in guinea pig isolated tracheal spirals. Several analogues show enhanced relaxant activity relative to cromakalim in this preparation and the rank order of potency for those substituents investigated at C-6 was CF3 greater than CN greater than C2H5 greater than aza greater than or equal to CH3. One compound, trans-3,4-dihydro-2,2-dimethyl-4-(2-oxopiperidin-1-yl)-7-(trifluor omethyl)-2H- 1-benzopyran-3-ol (24), was resolved into its two enantiomers and the activity was shown to reside essentially in the (+)-isomer, adding further support to the suggestion that the smooth muscle receptor for these potassium channel activators is stereoselective.

Journal of Medicinal Chemistry, 1991

Structural modifications of the potassium channel activator cromakalim (1) are described in which... more Structural modifications of the potassium channel activator cromakalim (1) are described in which the amide moiety at C-4 has been replaced by carboxamide and thiocarboxamide functions. Analogues in which the hydroxyl group at C-3 has been oxidized or removed are also disclosed. Such analogues display an interesting profile of smooth muscle relaxant activity in the guinea pig isolated trachea, not all of which appears to result from the opening of potassium channels, but few compounds retain useful in vivo activity. However, one compound in particular, 6-cyano-2,2-dimethyl-N-methyl-2H-1-benzopyran-4-thiocarboxamide (13) was shown to be a potent potassium channel activator in vitro and to provide prolonged protection to guinea pigs from the respiratory effects of inhaled histamine.

Bioorganic & Medicinal Chemistry Letters, 2001

The lipophilic 1-substituent in a series of 1-((amidolinked)-alkyl)-pyrimidones, inhibitors of re... more The lipophilic 1-substituent in a series of 1-((amidolinked)-alkyl)-pyrimidones, inhibitors of recombinant lipoprotein-associated phospholipase A(2), has been modified to give inhibitors of high potency in human plasma and enhanced physicochemical properties. Phenylpiperazineacetamide derivative 23 shows very promising oral activity.

Bioorganic & Medicinal Chemistry Letters, 1992

Abstract An efficient synthesis of the potassium channel activator, BRL 55834 (2), is described a... more Abstract An efficient synthesis of the potassium channel activator, BRL 55834 (2), is described and its absolute stereochemistry established as 3S,4R by X-ray crystallographic analysis of the corresponding (S)-α-methylbenzyl carbamate 12. BRL 55834 is the first compound of this pharmacological class to demonstrate selectivity for the smooth muscle of the airways compared with that of the vasculature.