An improved synthesis of 5-thio-d-ribose from d-ribono-1,4-lactone

5-Thio-d-ribopyranose was synthesized from d-ribono-1,4-lactone (1) by two approaches: (i) 5-bromo-5-deoxy-d-ribono-1,4-lactone (2) was successively transformed into 5-bromo-5-deoxy, 5-S-acetyl-5-thio or 5-thiocyanato-d-ribofuranose derivatives; appropriate treatment then lead to 5-thio-d-ribopyranose (7) in 46–48% overall yield and; (ii) 2 was transformed into the 5-S-acetyl-5-thio-d-ribono-1,4-lactone derivative (11). Reduction and deprotection of 11 afforded 5-thio-d-ribopyranose (7) in 57% overall yield.