368446-13-3Relevant academic research and scientific papers
Stereoselective synthesis of 8-oxabicyclo[3.2.1]octane-2,3,4,6,7-pentols and total asymmetric synthesis of 2,6-anhydrohepturonic acid derivatives and of β-C-manno-pyranosides suitable for the construction of (1 → 3)-C,C-linked trisaccharides
Gerber, Patrick,Vogel, Pierre
, p. 1363 - 1395 (2007/10/03)
Enantiomerically pure (+)-(1S,4S,5S,6S)-6-endo-(benzyloxy)-5-exo-{[(tert-butyl)dimethylsilyl]oxy}-7- oxa-bicyclo[2.2.1]heptan-2-one ((+)-5) and its enantiomer (-)-5, obtained readily from the Diels-Alder addition of furan to 1-cyanovinyl acetate, can be converted with high stereoselectivity into 8-oxabicyclo[3.2.1]octane-2,3,4,6,7-pentol derivatives (see 23-28 in Scheme 2). A precursor of them, (1R,2S,4R,5S,6S,7R,8R)-7-endo-(benzyloxy)-8-exo-hydroxy-3,9-dioxatricyclo[4.2.1. 02,4]non-5-endo-yl benzoate ((-)-19), is transformed into (1R,2R,5S, 6S,7R,8S)-6-exo,8-endo-bis(acetyloxy)-2-endo-(benzyloxy)-4-oxo-3,9- dioxabicycIo[3.3.1]non-7-endo-yl benzoate ((-)-43) (see Scheme 5). The latter is the precursor of several protected 2,6-anhydrohepturonic acid derivatives such as the diethyl dithioacetal (-)-57 of methyl 3,5-di-O-acetyl-2,6-anhydro-4-O-benzoyl-D-gycero-D-galacto-hepturonate (see Schemes 7 and 8). Hydrolysis of (-)-57 provides methyl 3,5-di-O-acetyl-2,6-anhydro-4-O-benzoyl-D-glycero-D-galacto-hepturonate 48 that undergoes highly diastereoselective Nozaki-Oshima condensation with the aluminium enolate resulting from the conjugate addition of Me2AlSPh to (1S,5S,6S,7S)-7-endo-(benzyloxy)-6-exo-{[(tert-butyl)dimethylsilyl]oxy}-8- oxabicyclo[3.2.1]oct-3-en-2-one ((-)-13) derived from (+)-5 (Scheme 12). This generates a β-C-mannopyranoside, i.e., methyl (7S)-3,5-di-O-acetyl-2,6-anhydro-4-O-benzoyl-7-C-[(1R,2S,3R,4S,5R,6S,7R)-6-endo- (benzyloxy)-7-exo-{[(tert-butyl)dimethylsilyl]oxy)-4-endo-hydroxy-2-exo- (phenylthio)-8-oxabicyclo[3.2.1]oct-3-endo-yl]-L-glycero-D-manno-heptonate ((-)-70; see Scheme 12), that is converted into the diethyl dithioacetal (-)-75 of methyl 3-O-acetyl-2,6-anhydro-4,5-dideoxy-4-C-{[methyl (7S)-3,5,7-tri-O-acetyl-2,6-anhydro-4-O-benzoyl-L-glycero-D-manno-heptonate]-7- C-yl)-5-C-(phenyl-sulfonyl)-L-glycero-D-galacto-hepturonate (76; see Scheme 13). Repeating the Nozaki-Oshima condensation to enone (-)-13 and the aldehyde resulting from hydrolysis of (-)-75, a (1 → 3)-C,C-linked trisaccharide precursor (-)-77 is obtained.
Total stereoselective syntheses of β-C-manno-pyranosides and of β- C(1←3)-linked disaccharides
Gerber, Patrick,Vogel, Pierre
, p. 3165 - 3168 (2007/10/03)
(-)-7-Oxabicyclo[2.2.1]hept-5-en-2-one has been convened to (-)-6-exo- [(tert-butyl)dimethylsilyloxy]-7-endo-benzyloxy-8-oxabieyclo[3.2.1]oct-3-en- 2-one and methyl 3,5-di-O-acetyl-2,6-anhydro-4-O-benzoyl-D-glycero-D-galacto- heptouronate that were condensed with Me2AlSPh into a single aldol which was transformed into a β-D-ManAp-CH(OAe)(1←3)-α-L-GulAp-CH(SEt)2 derivative.
