Publicações

Últimos trabalhos

SILVEIRA, C. C. ; RINALDI, Francieli ; GUADAGNIN, Rafael C . “Preparation and Reactivity of Chalcogenyl Phosphonates and Phosphane Oxides” Eur. J. Org. Chem. 2007, 4935.

The preparation of new bis[(diphenylphosphinoyl)methyl] sulfides, selenides, and tellurides is described by the reaction of (diphenylphosphinoyl)methyl p -toluenesulfonate with sodium chalcogenides. The title compounds are subjected to Horner-Wittig-type reactions with aldehydes and ketones to give symmetrical divinylic sulfides, selenides, and tellurides with preferential ( E ) stereochemistry. Unsymmetrical divinylic sulfides can be prepared by the use of an appropriate carbonyl compound.

PETRAGNANI, N.; MENDES, Samuel. R.; SILVEIRA, C. C. ” Tellurium tetrachloride. An improved method of preparation” Tetrahedron Lett. 2008 , 49 , 2371.

An efficient and practical synthesis of tellurium tetrachloride from elemental tellurium and sulfuryl chloride is described.

SILVEIRA, C. C.; SANTOS, P. C. S.; MENDES, S. R.; BRAGA, A. L. “A simple and general preparation of vinylic sulfides, selenides and tellurides” J. Organomet. Chem. 2008, 693, 3787.

A general method for the synthesis of vinylic chalcogenides by nucleophilic and Ni-catalyzed vinylic substitution on vinylic halides by phenyl chalcogenolates is described. The reactions were regio and stereoselective for the nickel catalyzed substitution, and mixture of isomers was observed for some examples in the thermal process in DMF.

SILVEIRA, C. C. ; RINALDI, F. ; BASSACO, M. M.; KAUFMAN, T. “Synthesis of 2-diphenylphosphinoyl-3,5-(diaryl)-3,4-dihydro-2H-thiopyrans by the reaction of a bis[(diphenylphosphinoyl)methyl]sulfide with chalcones “ Tetrahedron Lett. 2008, 49, 5782.

The NaH-promoted tandem Michael addition/intramolecular Horner Wittig reaction of bis(diphenylphosphinoylmethyl)sulfide with chalcones afforded 3,4-dihydro-2H-thiopyrans 3a-l in 78-88% yield

SILVEIRA, C. C.; MENDES, S. R.; LÍBERO, F. M. “Glycerin and CeCl3·7H2O: a new and efficient recyclable medium for the synthesis of bis(indolyl)methanes” Tetrahedron Lett. 2009, 50, 6060.

Glycerin and CeCl3·7H2O were successfully used in recyclable catalytic system for the synthesis of several bis(indolyl)methanes in good to excellent yields through the reaction of indoles with aldehydes. The method is applicable to aliphatic and aromatic aldehydes, and the mixture of glycerin and CeCl3·7H2O can be reused up to five times without special treatment and with comparable yields.

SILVEIRA, C. C.; RINALDI, Francieli ; GUADAGNIN, Rafael C. “Stereoselective Synthesis of Alkynyl Vinyl Chalcogenides via Horner-Wittig Reaction” Synthesis 2009, 469.

New (diphenylphosphoryl)methyl phenylethynyl sulfides, selenides, or tellurides were prepared by the reaction of (diphenylphosphoryl)methyl p-toluenesulfonate with alkynethiols, -selenols, or -tellurols at room temperature. The (diphenylphosphoryl)methyl phenylethynyl sulfides, selenides, or tellurides reacted with aldehydes and cyclic ketones to give the corresponding alkynyl vinyl sulfides, selenides, or tellurides, with preferential E-stereochemistry, in a Horner-Wittig-type reaction.

SILVEIRA, C. C.; LARGHI, E. L.; MENDES, S. R.; BRACCA, A. B. J.; RINALDI, F., KAUFMAN, T. S. ” Electrocyclization-Mediated Approach to 2-Methyltriclisine, an Unnatural Analog of the Azafluoranthene Alkaloid Triclisine” Eur. J. Org. Chem. 2009, 4637.

The synthesis of 2-methyltriclisine, an unnatural analog of the azafluoranthene alkaloid triclisine, is reported. The synthesis was achieved in 10 steps and 21 % overall yield from 2-bromo-3,4-dimethoxybenzaldehyde, through the intermediacy of 3,4-dimethoxyfluoren-9-one. Construction of the heterocyclic ring entailed the para-Claisen rearrangement of an allyl-4-fluorenyl ether, followed by isomerization of the resulting 2-allylfluoren-9-one and a microwave-assisted electrocyclization of the aza 6tt-electron system formed by oximation of its carbonyl function.

SILVEIRA, C. C. ; MENDES, Samuel R.; ROSA, Daniel ; ZENI, Gilson . “Cerium(III)-Mediated Efficient and Stereoselective Hydrochalcogenation of Terminal Alkynes”. Synthesis 2009, 4015.

Vinylic chalcogenides were synthesized stereospecifically by hydrochalcogenation of propargylic amines or alcohols mediated by cerium(III) chloride. The products were obtained in good yields and with high regio- and stereoselectivities.

SILVEIRA, Claudio C. ; RINALDI, Francieli ; BASSACO, Mariana M. ; KAUFMAN, Teodoro S. “Synthesis of 2-diphenylphosphinoyl-3,5-diaryl-3,4-dihydro-2H-telluropyrans by reaction of chalcones with bis[(diphenylphosphinoyl)methyl]telluride”. Tetrahedron Lett. 2010, 51, 4563.

The NaH-promoted tandem Michael addition/intramolecular Wittig–Horner reaction of bis[(diphenylphosphinoyl) methyl]telluride with chalcones stereoselectively afforded trans-2-diphenylphosphinoyl-3,5-diaryl-3,4-dihydro-2H-telluropyran derivatives in 51–72% yield, under mild conditions.

SILVEIRA, Claudio C. ; MENDES, Samuel R. ; WOLF, Lucas ; MARTINS, Guilherme M. “The use of anhydrous CeCl3 as a catalyst for the synthesis of 3-sulfenyl indoles”. Tetrahedron Lett. 2010, 51, 2014.

Anhydrous CeCl3 was successfully used as a catalyst for the synthesis of several 3-sulfenyl indoles in good to excellent yields through the reaction of indole with N-(alkylthio) and N-(arylthio)phthalimides in DMF.

SILVEIRA, Claudio C. ; MENDES, Samuel R. ; WOLF, Lucas ; MARTINS, Guilherme M. “Anhydrous CeCl3 catalyzed C3-selective propargylation of indoles with tertiary alcohols”. Tetrahedron Lett. 2010, 51, 4560.

Anhydrous CeCl3 was successfully used as catalyst for the synthesis of several 3-propargyl indoles in good yields through the reaction of indole with propargyl alcohols in nitromethane.

SILVEIRA, C. C.; MENDES, Samuel R.; ZIEMBOWICZ, F. I.; LENARDÃO, E. J.; PERIN, Gelson . “The use of anhydrous CeCl3 as a recyclable and selective catalyst for the acetalization of aldehydes and ketones”. J. Braz. Chem. Soc. 2010, 21, 371.

An efficient, clean, chemoselective and solvent-free method for the synthesis of ketone and aldehyde dimethyl acetals was developed using trimethyl orthoformate and commercially available anhydrous CeCl3 as a recyclable catalyst. The method is general and affords the protected carbonyl compounds in good yields and under mild conditions, including aryl and alkyl ketones and activated aldehydes. The catalyst could be utilised directly for 3 cycles, without significant loss of activity.

SILVEIRA, Claudio; MENDES, Samuel ; LÍBERO, Francieli “Solvent-Free Anti-Markovnikov Addition of Thiols to Alkenes Using Anhydrous Cerium(III) Chloride as Catalyst”. Synlett 2010, 790.

The anti-Markovnikov addition of thiols to alkenes using CeCl3 as catalyst is described. The products were obtained in good to excellent yields. The reaction occurred under solvent-free conditions at room temperature.