Synthesis of 4-O-(1-deoxy-d-alditol-1-yl)-d-alditols from disaccharide derivatives

Selective C−O Bond Cleavage of Sugars with Hydrosilanes Catalyzed by Piers’ Borane Generated In Situ

“…Although several transition-metalbased heterogeneous catalytic protocols are known for the hydrogenation of carbohydrates to linear polyols, [15] the metal-free catalytic version remains less explored. [16] Ah ydrosilylative reduction of as ilyl-protected anomeric mixture of d-glucose 4a with TMDS proceeded slowly in the presence of 1 (1 mol %) in 1,4-dioxane to furnish ring-opening product 5a-TMS,albeit in low yield, after 14 days.Incontrast, 4b with the opposite C2 configuration to that of 4a was found to be more reactive under identical reaction conditions, providing 5bin 94 %yield after 7days.Increasing the catalyst loading to 3mol %r esulted in the reaction being completed after 4days.I na ddition, CÀOb ond cleavage of substrate 4c with the opposite C4 configuration to that of 4a occurred in the presence of 1 (3 mol %) to afford the corresponding Scheme 2. a) One-pot synthesis of (C 6 F 5 ) 2 BOH 1 from (C 6 F 5 ) 2 BPh and H 2 O. b) Generation of (C 6 F 5 ) 2 BH 2 in situ. c) Trapping of (C 6 F 5 ) 2 BH 2 (Piers' borane) with abase (2-SMe 2 or 3).…”

Selective C−O Bond Cleavage of Sugars with Hydrosilanes Catalyzed by Piers’ Borane Generated In Situ

“…Although several transition-metalbased heterogeneous catalytic protocols are known for the hydrogenation of carbohydrates to linear polyols, [15] the metal-free catalytic version remains less explored. [16] Ah ydrosilylative reduction of as ilyl-protected anomeric mixture of d-glucose 4a with TMDS proceeded slowly in the presence of 1 (1 mol %) in 1,4-dioxane to furnish ring-opening product 5a-TMS,albeit in low yield, after 14 days.Incontrast, 4b with the opposite C2 configuration to that of 4a was found to be more reactive under identical reaction conditions, providing 5bin 94 %yield after 7days.Increasing the catalyst loading to 3mol %r esulted in the reaction being completed after 4days.I na ddition, CÀOb ond cleavage of substrate 4c with the opposite C4 configuration to that of 4a occurred in the presence of 1 (3 mol %) to afford the corresponding Table 1: Scope of selective CÀObond cleavage of sugars. [a] [a] Reaction conditions:(C 6 F 5 ) 2 BOH (1,1mol %), substrate (0.4 mmol), and TMDS (4 equiv,1.6 mmol) in 1,4-dioxane (0.4 mL) for 1-14 days at 25 8 8C.…”