Showing papers by "Marcello Tiecco published in 2004"
TL;DR: A new and convenient method for the stereospecific synthesis of variously substituted 1,3-oxazolidin-2-ones from the easily available beta-hydroxyalkyl phenyl selenides is presented.
Abstract: A new and convenient method for the stereospecific synthesis of variously substituted 1,3-oxazolidin-2-ones from the easily available beta-hydroxyalkyl phenyl selenides is presented. After transformation into the N-tosyl or N-benzoyl carbamates, the selenides were oxidized to the corresponding selenones. The key step of the process is the ring-closure reaction, which occurs by stereospecific intramolecular nucleophilic substitution of the selenone group by the nitrogen atom of the carbamate. Enantiomerically pure 1,3-oxazolidin-2-one derivatives can be easily prepared by using enantiomerically pure beta-hydroxyalkyl phenyl selenides as starting materials.
38 citations
TL;DR: The first example of a kinetic resolution process promoted by electrophilic selenium reagents is reported, leading to the regiospecific formation of the corresponding addition products with a very high level of facial selectivity.
37 citations
TL;DR: In this paper, Se-phenyl selenocarboxylates were easily converted into the corresponding esters and amides, which is compatible with a broad range of oxygen-and nitrogen-containing functional groups.
34 citations
TL;DR: The tetrahydrofuran derivatives thus obtained were finally deselenenylated with triphenyltin hydride and AIBN as mentioned in this paper, and the reaction of these allylic derivatives with electrophilic phenylselenium reagents afforded selenium containing tetrahdrofurans as the result of a stereospecific 5-exo-trig cyclization.
Abstract: Starting from commercially available enantiomerically pure epoxides, enantiomerically pure substituted tetrahydrofurans were prepared using simple conversions promoted by organoselenium reagents. The first step consisted in the opening of the epoxides with phenylselenolate anions to afford hydroxyalkyl phenyl selenides. The PhSe group was then substituted by an allyl group by treatment with allyltributyltin and AIBN. The reaction of these allylic derivatives with electrophilic phenylselenium reagents afforded selenium containing tetrahydrofurans as the result of a stereospecific 5-exo-trig cyclization. The tetrahydrofuran derivatives thus obtained were finally deselenenylated with triphenyltin hydride and AIBN.
32 citations
TL;DR: In this paper, the PhSe group in the C-4 position of tetrahydrofurans was substituted by an allyl group using allyltributylstannane in the presence of AIBN.
Abstract: Olefinic diols, prepared from ( R )-(+)-2,2-dimethyl-1,3-dioxolane-4-carboxaldehyde via olefination and hydrolysis, were converted into enantiomerically pure hydroxy substituted tetrahydrofuran derivatives by cyclization using N -phenylselenophthalimide and BF 3 . The PhSe group in the C-4 position of these tetrahydrofurans was then substituted by an allyl group using allyltributylstannane in the presence of AIBN. The selenium promoted cyclizations of the allyl tetrahydrofurans in which the OH and the allyl groups are trans to each other formed the enantiopure perhydrofuro[3,4- b ]pyrans, while the cyclization of the allyl tetrahydrofurans in which the OH and the allyl groups are cis gave rise to the perhydrofuro[3,4- b ]furans. These bicyclic products were finally deselenenylated with triphenyltin hydride and AIBN.
28 citations
TL;DR: Asymmetric aldol condensations using titanium enolates of (R )-camphorselenoacetone and of methyl ( R )-Camphorseleneacetate are reported in this paper.
Abstract: Asymmetric aldol condensations using titanium enolates of ( R )-camphorselenoacetone and of methyl ( R )-camphorselenoacetate are reported. The reactions with aromatic, α,β-unsaturated or aliphatic aldehydes proceed with good chemical yields giving a mixture of the syn and anti aldols. These diastereoisomers were easily separated by column chromatography. The two syn diastereoisomers were obtained in enantiomerically pure form.
17 citations
TL;DR: In this paper, the PhSe group in the C-4 position of tetrahydrofurans was substituted by an allyl group using allyltributylstannane in the presence of AIBN.
Abstract: Olefinic diols, prepared from ( R )-(+)-2,2-dimethyl-1,3-dioxolane-4-carboxaldehyde via olefination and hydrolysis, were converted into enantiomerically pure hydroxy substituted tetrahydrofuran derivatives by cyclization using N -phenylselenophthalimide and BF 3 . The PhSe group in the C-4 position of these tetrahydrofurans was then substituted by an allyl group using allyltributylstannane in the presence of AIBN. The selenium promoted cyclizations of the allyl tetrahydrofurans in which the OH and the allyl groups are trans to each other formed the enantiopure perhydrofuro[3,4- b ]pyrans, while the cyclization of the allyl tetrahydrofurans in which the OH and the allyl groups are cis gave rise to the perhydrofuro[3,4- b ]furans. These bicyclic products were finally deselenenylated with triphenyltin hydride and AIBN.