129829-54-5Relevant articles and documents
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 Syntheses of (-)-Conduritol B ((-)-1L-Cyclohex-5-ene-1,3/2,4-tetrol) and of (+)-Conduritol F ((+)-1D-Cyclohex-5-ene-1,2,4/3-tetrol). Determination of the Absolute Configuration of (+)-Leucanthemitol
Drian, Claude Le,Vionnet, Jean-Paul,Vogel, Pierre
, p. 161 - 168 (2007/10/02)
The 'naked sugar' (+)-(1R,2R,4R)-2-endo-cyano-7-oxabicyclohept-5-en-2-exo-yl acetate ((+)-4) was converted (7 steps , 45percent overall) with high stereoselectivity into (-)-(4R,5S,6R)-4,5,6-tris(oxy)cyclohex-2-en-1-one (
Acid-Catalyzed Rearrangement of 5,6-exo-Epoxy-7-oxabicyclohept-2-yl Derivatives. Migratory Aptitudes of Acyl vs. Alkyl Groups in Wagner-Meerwein Transpositions
Drian, Claude Le,Vogel, Pierre
, p. 1703 - 1720 (2007/10/02)
In the presence of HSO3F/Ac2O in CH2Cl2, 2-exo- and 2-endo-cyano-5,6-exo-epoxy-7-bicyclohept-2-yl acetates (6a,b) gave products derived from the epoxide-ring opening and a 1,2-shift of the unsubstituted alkyl group (? bond C(3)-C(4)).In contrast, under similar conditions, the 5,6-exo-epoxy-7-oxabicycloheptan-2-one (6c) gave 5-oxo-2-oxabicycloheptane-3,7-diyl diacetates 20 and 21 arising from the 1,2-shift of the acyl group.Acid treatment of 5,6-exo-epoxy-2,2-dimethoxy-7-oxabicycloheptane (6d) and of 5,6-exo-epoxy-2,2-bis(benzyloxy)-7-oxabicycloheptane (6c) gave minor products arising from epoxide ring opening and the 1,2-shift of ? bond C(3)-C(4) and major products (25,29) arising from the 1,3-shift of a methoxy and benzyloxy group, respectively.Under similar conditions, 5,6-exo-epoxy-2,2-ethylenedioxy-7-oxabicycloheptane (6f) gave 1,1-(ethylenedioxy)-2-(2-furyl)ethyl acetate (32, major) and a minor product 33 arising from the 1,2-shift of ? bond C(3)-C(4).The following order of migratory aptitudes for 1,2-shifts toward electron-deficient centers has been established: acyl > alkyl > alkyl α-substituted with inductive electron-withdrawing groups.This order is valid for,competitive Wagner-Meerwein rearrangements involving equilibria between carbocation intermediates with similar exothermicites.
