Stereoselective synthesis of 4-C-methyl-2,3,5-tri-O-benzyl-d-ribofuranose and 4-C-methyl-2,3,5-tri-O-benzyl-l-lyxofuranose

Sugar intermediates 4-C-methyl-2,3,5-tri-O-benzyl-d-ribofuranose (8b) and 4-C-methyl-2,3,5-tri-O-benzyl-l-lyxofuranose (8a) were synthesized by addition of alkylithium reagents to pentanones 3a,b. The nucleophilic additions proceeded with good stereoselectivity and good yields to give the titled compounds in four steps from perbenzylated methyl d-ribofuranoside and methyl 5′-deoxy-d-ribofuranoside.