50256-79-6Relevant academic research and scientific papers
Higher glycosamino acid precursors: C7 and C8 aminodialdoses via regio- and stereoselective [3+2] cycloaddition of vinyl trimethylsilane to C-glycosyl nitrones
Borrachero, Pastora,Cabrera-Escribano, Francisca,Dianez, Ma Jesus,Estrada, Ma Dolores,Gomez-Guillen, Manuel,Castro, Amparo Lopez,Perez-Garrido, Simeon,Torres, Ma Isabel
, p. 2025 - 2038 (2002)
Protected C7 and C8 aminodialdoses were prepared stereoselectively from readily available C5 and C6 monosaccharide N-benzyl nitrones, by regio- and diastereoselective 1,3-dipolar cycloaddition reactions with vinyl trimethylsilane, followed by acetyl chloride-mediated cleavage of the 5-(trimethylsilyl)isoxazolidine formed. The cycloaddition reaction took place in moderate to good global yields (67-74%); estimation of diastereoselectivities from isolated yields showed total endo preference for the reaction of the D-galacto configured nitrone and high endo preference for the D-ribo analogue, but exo preference for the D-xylo configured substrate. Attack on the re face of the nitrone was predominant in all cases. The absolute configuration of one of the protected 3-(α-D-galacto-pentopyranos-5-yl)isoxazolidine products was assigned by X-ray crystallographic analysis, allowing correlation of the configuration at the new stereogenic centre in the corresponding aminodialdose. For non-crystalline isoxazolidines, configurations were assigned on the basis of NOESY experiments and/or chemical correlation. Combined yields of aminodialdoses coming from isoxazolidines having identical configuration at C(3) sometimes reached high values (up to 90%). These compounds are precursors of higher-chain glycosamino acids.
