46 



W. G. OVEREND AND M. STACEY 



D-ribose containing both acetate and benzoate groupings are known. 

 Kenner et al}^^ synthesized 2,3,4-tri-0-acetyl-5-0-benzoyl-D-ribose, and 

 l-0-acetyl-2,3,5-tri-0-benzoyl-D-ribose has been prepared from guano- 

 sine.2^® 



(3) Acetals. Two products are obtained when D-ribose is treated with 

 acetone in the presence of sulfuric acid and anhydrous copper sulfatej^^" 

 one of which is crystalHne and the other syrupy. The crystalhne material 

 is unreactive and is considered to be 2,3-0-isopropylidene-l ,5-anhydro-D- 

 ribofuranose. The syrupy material, which is the major product, can be 

 purified via its di-0-acetyl derivative and by the usual methods of classical 

 carbohydrate chemistry and has been shown to be 2,3-0-isopropylidene- 

 D-ribofuranose. If D-ribose is treated with acetone and methanol in the 

 presence of sulfuric acid and anhydrous copper sulfate, methyl 2,3-0-iso- 

 propylidene-D-ribofuranoside is obtained directly. ^^* This compound has 

 been used as an intermediate in syntheses of naturally occurring ribose 

 derivatives. Attempts to acetonate methyl D-ribopyranoside gave mixtures 

 of methyl mono-0-isopropylidene-D-ribo-furanoside and -pyranoside, and 

 obviously some rearrangement of the lactol ring occurred during the 

 reaction. ^^^ 



(4) Anhydrides. In an attempt to prepare 1 ,2,3-tri-0-acetyl-D-ribo- 

 f uranose by detritylation of 1,2, 3-tri-0-acetyl-5-0-trityl-D-ribof uranose 

 with hydrogen bromide in glacial acetic acid at 0°, Bredereck et al.^^ iso- 

 lated an acetate which on hydrolysis afforded an anhydride of D-ribose. 

 The structure assigned to this compound by these workers was D-ribo- 

 san(l,4) (3(1,5) (XLII). The anhydride gave a positive test for vicinal 



CH 



H— C— OH 



H— C— OH 



H— C— O— 



— OCH2 

 XLII 



CH- 



H— C— OH 



H— C— OH 



H— C— 0- 



-OCH2 



CH2O 



-O— C— F 



HO— C— H 



HO— C— H 



:CH 



XLIII 



hydroxyl groups and was reducing to Fehling's solution after acidic hy- 

 drolysis. Barker and Lock^^^ and Jeanloz^"*^ reexamined the compound and 

 found that it was bimolecular. A crystalline tetra-0-methyl-di-D-ribose 



^^^ G. W. Kenner, H. J. Rodda, and A. R. Todd, /. Chem. Soc. 1949, 1613. 



"6 F. Weygand and W. Sigmund, Chem. Ber. 86, 160 (1953). 



2" P. A. Levene and E. T. Stiller, /. Biol. Chem. 106, 421 (1934). 



^^ R. W. Jeanloz, G. R. Barker, and M. V. Lock, Nature 167, 42 (1951). 



