The sulphoxidation of the enol ethers of some acyldithiolanes using the Sharpless epoxidation rea... more The sulphoxidation of the enol ethers of some acyldithiolanes using the Sharpless epoxidation reagents followed by fluorolysis results in better overall stereoselectivity than direct oxidation of the acyldithiolane thus providing a highly stereoselective route to acyldithiolane sulphoxides. Fluorolysis under acid conditions of non terminal enol ethers results in complete recemisation of the product.
An efficient, practical and stereoselective route for the preparation of several polyols and thei... more An efficient, practical and stereoselective route for the preparation of several polyols and their corresponding lactols and lactones is described. They are promising precursors for the synthesis of several structurally interesting compounds.
Skip to Main Content. Wiley Online Library will be disrupted 5 Nov from 10-12 GMT for monthly mai... more Skip to Main Content. Wiley Online Library will be disrupted 5 Nov from 10-12 GMT for monthly maintenance. ...
ABSTRACT An efficient method for the N-arylation of primary and some secondary amines using 2-hal... more ABSTRACT An efficient method for the N-arylation of primary and some secondary amines using 2-halocyclohex-2-enones in an aliphatic-to-aromatic transformation in the presence of a substoichiometric amount of pTsOH has been developed.
ABSTRACT Three protected new gallotannins, namely the 6′-O-(tri-O-methylgalloyl)-2,3,4,6,1′,3′,4′... more ABSTRACT Three protected new gallotannins, namely the 6′-O-(tri-O-methylgalloyl)-2,3,4,6,1′,3′,4′-hepta-O-acetylsucrose, the 6′-O-(tri-O-methylgalloyl)-2,3,4,6,1′,3′,4′-hepta-O-benzoylsucrose and the 6,6′-di-O-tert-butyldiphenylsilyl-1′-O-(tri-O-methylgalloyl)-2,3,4,3′,4′-penta-O-acetylsucrose have been prepared in four short sequences from sucrose. Methods for rapid galloylation have been studied in order to avoid simultaneous acyl transfer reactions. A method for the deprotection of a tert-butyldiphenylsilyl ether has been developed which avoids the intramolecular migration of a benzoate group.
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
6-O-methacryloyl-α-d-glucoside 2 and 4-bromophenyl-6-O-methacryloyl-d-glucothioside 7, obtained b... more 6-O-methacryloyl-α-d-glucoside 2 and 4-bromophenyl-6-O-methacryloyl-d-glucothioside 7, obtained by enzyme-catalyzed synthesis, have been homo-polymerized and copolymerized with styrene by a free radical process, yielding polymer materials with sugar moieties, attached to the polymer backbone via ester linkages. The results demonstrated that modifying the structural features of the monomers greatly affected the thermal and rheological properties of the polymers. The polymer materials obtained have been characterized by NMR, MALDI-MS, DSC, AFM, and EWC (equilibrium water content). The AFM images indicated the formation of spherical and core-shell polymeric microparticles.
A short synthesis of the natural potent cytotoxic agent (−)-muricatacin 1 and related unsaturated... more A short synthesis of the natural potent cytotoxic agent (−)-muricatacin 1 and related unsaturated lactones from a versatile common intermediate, dienedioate 2, derived from d-mannitol or tartaric acid, is described. The strategy depends upon the desymmetrization of 7 by dihydroxylation and elaboration of the hydroxy alkyl sidechain. A route to unsaturated lactones is also described using a cis selective Wittig
ABSTRACT Novel chiral C2-symmetric bis(oxazolines) were prepared from tartaric acid. They were ap... more ABSTRACT Novel chiral C2-symmetric bis(oxazolines) were prepared from tartaric acid. They were applied as ligands in the copper-catalyzed conjugate addition of diethylzinc to chalcone and 2-cyclohexenone. Maximum enantiomeric excesses of 50% and 53% were obtained, respectively. The sense of induction was found to depend on the configuration of the stereogenic centre in the oxazoline ring, and not on the stereogenic centres of the 1,4-dioxane backbone.
The sulphoxidation of the enol ethers of some acyldithiolanes using the Sharpless epoxidation rea... more The sulphoxidation of the enol ethers of some acyldithiolanes using the Sharpless epoxidation reagents followed by fluorolysis results in better overall stereoselectivity than direct oxidation of the acyldithiolane thus providing a highly stereoselective route to acyldithiolane sulphoxides. Fluorolysis under acid conditions of non terminal enol ethers results in complete recemisation of the product.
An efficient, practical and stereoselective route for the preparation of several polyols and thei... more An efficient, practical and stereoselective route for the preparation of several polyols and their corresponding lactols and lactones is described. They are promising precursors for the synthesis of several structurally interesting compounds.
Skip to Main Content. Wiley Online Library will be disrupted 5 Nov from 10-12 GMT for monthly mai... more Skip to Main Content. Wiley Online Library will be disrupted 5 Nov from 10-12 GMT for monthly maintenance. ...
ABSTRACT An efficient method for the N-arylation of primary and some secondary amines using 2-hal... more ABSTRACT An efficient method for the N-arylation of primary and some secondary amines using 2-halocyclohex-2-enones in an aliphatic-to-aromatic transformation in the presence of a substoichiometric amount of pTsOH has been developed.
ABSTRACT Three protected new gallotannins, namely the 6′-O-(tri-O-methylgalloyl)-2,3,4,6,1′,3′,4′... more ABSTRACT Three protected new gallotannins, namely the 6′-O-(tri-O-methylgalloyl)-2,3,4,6,1′,3′,4′-hepta-O-acetylsucrose, the 6′-O-(tri-O-methylgalloyl)-2,3,4,6,1′,3′,4′-hepta-O-benzoylsucrose and the 6,6′-di-O-tert-butyldiphenylsilyl-1′-O-(tri-O-methylgalloyl)-2,3,4,3′,4′-penta-O-acetylsucrose have been prepared in four short sequences from sucrose. Methods for rapid galloylation have been studied in order to avoid simultaneous acyl transfer reactions. A method for the deprotection of a tert-butyldiphenylsilyl ether has been developed which avoids the intramolecular migration of a benzoate group.
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
6-O-methacryloyl-α-d-glucoside 2 and 4-bromophenyl-6-O-methacryloyl-d-glucothioside 7, obtained b... more 6-O-methacryloyl-α-d-glucoside 2 and 4-bromophenyl-6-O-methacryloyl-d-glucothioside 7, obtained by enzyme-catalyzed synthesis, have been homo-polymerized and copolymerized with styrene by a free radical process, yielding polymer materials with sugar moieties, attached to the polymer backbone via ester linkages. The results demonstrated that modifying the structural features of the monomers greatly affected the thermal and rheological properties of the polymers. The polymer materials obtained have been characterized by NMR, MALDI-MS, DSC, AFM, and EWC (equilibrium water content). The AFM images indicated the formation of spherical and core-shell polymeric microparticles.
A short synthesis of the natural potent cytotoxic agent (−)-muricatacin 1 and related unsaturated... more A short synthesis of the natural potent cytotoxic agent (−)-muricatacin 1 and related unsaturated lactones from a versatile common intermediate, dienedioate 2, derived from d-mannitol or tartaric acid, is described. The strategy depends upon the desymmetrization of 7 by dihydroxylation and elaboration of the hydroxy alkyl sidechain. A route to unsaturated lactones is also described using a cis selective Wittig
ABSTRACT Novel chiral C2-symmetric bis(oxazolines) were prepared from tartaric acid. They were ap... more ABSTRACT Novel chiral C2-symmetric bis(oxazolines) were prepared from tartaric acid. They were applied as ligands in the copper-catalyzed conjugate addition of diethylzinc to chalcone and 2-cyclohexenone. Maximum enantiomeric excesses of 50% and 53% were obtained, respectively. The sense of induction was found to depend on the configuration of the stereogenic centre in the oxazoline ring, and not on the stereogenic centres of the 1,4-dioxane backbone.
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Papers by Maria Silva