RESUMO
A perfluoroalkylidene lithium mediated cyclisation approach for the enantioselective synthesis of a tetrafluorinated aldose (ribose) and of a tetrafluorinated ketose (fructose), both in the furanose and in the pyranose form, is described.
Assuntos
Ribose/síntese química , Ciclização , Flúor , Frutose/análogos & derivados , Frutose/síntese química , Ribose/análogos & derivados , EstereoisomerismoRESUMO
[reactions: see text] A concise synthesis of highly functionalized cyclopentane derivatives via a Brook rearrangement mediated stereoselective linchpin cyclization reaction involving tert-butyldimethylsilyl-1,3-dithianyllithium and homochiral 1,4-bis-epoxides is described.
Assuntos
Compostos de Epóxi/química , Compostos Organometálicos/química , Pentoses/síntese química , Ciclização , Lítio/química , Estrutura Molecular , Pentoses/química , Silanos/química , EstereoisomerismoRESUMO
On the basis of our previously described selective protection of arabitol as its 1,2:4,5-bis-pentylidene acetal 5, we report a straightforward synthesis of the novel "pseudo"-C(2)-symmetric 3-azido-1,2:4,5-diepoxypentane building block 4 in 6 steps from arabitol. Using a similar synthetic route, an improved synthesis of the C(2)-symmetrical 1,2:4,5-bis-epoxypentane building block 1 is described, also in 6 steps from arabitol. Both enantiomers of 1 and 4 are accessible, and all reactions involved are easily amenable for large-scale synthesis.
Assuntos
Azidas/síntese química , Compostos de Epóxi/síntese química , Álcoois Açúcares/química , Azidas/química , Compostos de Epóxi/química , Estrutura Molecular , EstereoisomerismoRESUMO
A short synthesis of the homochiral disubstituted butenolide 1 is described in four steps from arabitol. The key steps are the selective kinetic protection of arabitol and the cyclization of 11 to form the butenolide ring. This last transformation represents a rare example of a fully stereoselective cyclitive desymmetrization process of a "pseudo"-C2-symmetric substrate.