Synthesis of New 2,3-Unsaturated O-Glycosides Through Ferrier Rearrangement1

<b>SYNTHESIS OF 2,3-UNSATURATED FURANIC HEX- AND PENT-ENOPYRANOSIDE EMPLOYING THE FERRIER REARRANGEMENT</b>

“…Starting furanic alcohols 2c, 2d and 2e were respectively prepared with sodium borohydride (NaBH 4 ) of 5-methyl-2-hydroxymethylfurfural, by addition of furyllithium on ethylene oxide [12] and reduction in two steps of 3-(2-furyl)-acrolein [13] in good yields. The reaction of alcohols 2a-e with glucal 1, carried out in presence of boron trifluoride [7] (method A), ferric chloride [11] (method B) and CAN [10] (method C), afforded the corresponding 2,3-unsaturated glucopyranosides 3a-e (Table 1). With boron trifluoride as the catalyst (method A), the yields from monosubstitued furanic alcohols 2a, 2d and 2e increased with the lentgh of carbon chain while the yields were lower than those of method A in presence of ferric chloride (method B).…”

“…The selectivity / was small influenced by the catalyst used and was in favor of -anomers. The amount ofanomers ranged from 70 to 94 % according to the catalyst employed and was calculated from 13 C NMR spectra [11]. The mixture was separated by chromatography column under deacetylated form and each anomer was reacetylated to produce 3 and 3 .…”

“…In recent publication, we reported the glycosidation of 3,4,6-tri-O-acetyl-D-glucal 1 with six alcohols among which furanic alcohols 2a and 2b in presence of Lewis acid [11]. In our ongoing research on the glycosidation of glycals, we report here the glycosidation of 3,4,6-tri-Oacetyl-D-glucal 1 (Scheme 1) and 3,4-di-O-acetyl-D-xylal 4 (Scheme 2) with various furanic alcohols using ceric(IV) ammonium nitrate under neutral reaction conditions or Lewis acidcatalyst.…”

Synthesis, Configurational and Conformational Studies of Six Amino Sugar Precursors Formed by [3+2]Cycloaddition of Alkylnitrile Oxides to Enone Sugars

“…6,7 Alkaline hydrolysis of 3a-c yielded 4a-c in good yields (>86%). The reaction of alcohols 2a-c and this unsaturated carbohydrate in the presence of Montmorillonite K-10, according to the literature procedure, went smoothly giving 3a-c in excellent yields.…”

Environmentally Benign Synthesis of 2,3-Unsaturated Glycopyranosides in Task-Specific Ionic Liquid

“…They have been successfully used as chiral building blocks in the multi-step synthesis of several antibiotics [3,4]. Conventionally, 2,3-unsaturated glycosides are prepared by the allylic rearrangement of acyloxy glycals (popularly known as Ferrier Rearrangement) catalyzed by a Lewis acid [5,6]. Because of their synthetic utility several reports have appeared in the literature for the improvement of the Ferrier reaction using a variety of metallic and non-metallic catalysts [7][8][9][10][11][12][13][14][15][16][17].…”