201233-15-0Relevant articles and documents
Palladium-Mediated Cyclization on Carbohydrate Templates. 1. Synthesis of Enantiopure Bicyclic Compounds
Nguefack, Jean-Flaubert,Bolitt, Veronique,Sinou, Denis
, p. 1341 - 1347 (1997)
The bromo unsaturated carbohydrates 3a and 9 were prepared from ethyl 4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-enopyranoside (1a) and (7) by deacetylation followed by monosilylation with TBDMSC1 and then alkylation with BrCH2CBr=CH2. The threo analogues 6 and 10 were obtained using the same methodology after inversion at C-4 via a Mitsunobu reaction. The N- and C-analogues 4b and 5 were prepared by palladium alkylation of the carbonate 2d with TsNHCH2CBr=CH2 and (CO2Me)2CHCH2CBr=CH2, respectively. Treatment of the unsaturated carbohydrates 3a and 9 with a catalytic amount of Pd(OAc)2/PPhs in CH3CN/H2O in the presence of Bu4NHSO4 and NEt3 afforded the bicyclic compound 14a. The N- and C-analogues 14b and 14c were obtained using the same conditions and starting, respectively, from 4b and 5. On the other hand, treatment of the threo derivatives 6 and 10 under these conditions gave the furanic structure 15. In the case of compound 3a, performing the reaction in the presence of sodium formate yielded the bicyclic 2-deoxy carbohydrate 17.
Synthesis of α- and β-C-Aryl Δ2-Glycopyranosides from p-tert-Butylphenyl Δ2-Glycopyranosides via Grignard Reagents
Moineau, Christophe,Bolitt, Véronique,Sinou, Denis
, p. 582 - 591 (2007/10/03)
Treatment of p-tert-butylphenyl 4,6-di-O-benzyl-2,3-dideoxy-α-D-erythro-hex-2-enopyranoside (1aα) or the 4,6-di-O-(tert-butyldimethylsilyl) analogue (1bα) with various functionalized arylmagnesium bromides in the presence of a catalytic amount of PdCl2(dppf) at 25°C in THF afforded the corresponding unsaturated C-arylglycosides 2-14 having the α-configuration in quite good yields. Benzyl-, allyl-, and vinylmagnesium bromides gave also the corresponding unsaturated α-C-glycosides 15-18, although in lower yields. When the same reaction was performed in the presence of NiCl2(dppe) as the catalyst at -40°C, only the formation of the corresponding unsaturated C-arylglycosides having the β-configuration was observed. As expected, reaction of phenylmagnesium bromide with p-tert-butylphenyl 4,6-di-O-benzyl-2,3-dideoxy-β-D-erythro-hex-2-enopyranoside (1aβ) in the presence of NiCl2(dppe) gave only the unsaturated β-C-phenylglycoside 2aβ, while palladium-catalyzed reaction led to the preponderant formation of C-phenylglycoside 2aα. Reaction of PhMgBr with p-tert-butylphenyl 4-O-benzyl-2,3,6-trideoxy-α-L-erythro-hex-2-enopyranoside (20) afforded stereospecifically the unsaturated α- and β-C-phenylglycoside 25 in the presence of PdCl2-(dppf) and NiCl2(dppe), respectively.
An easy and efficient preparation of aryl α-O-Δ2-glycosides
Frappa,Sinou
, p. 2941 - 2951 (2007/10/03)
Ferrier reaction between acetylglycals and p-NO2, m-NO2 and p-t-butylphenol after recrystallization gave aryl O-Δ2-glycosides as the pure α anomers. Deacetylation of these compounds and benzylation of the crude diol led to
