50 W. G. OVEREND AND M. STACEY 



acid, then the methyl glycoside of the 2-deoxysugar is obtained. For 

 example, L-arabinal was converted into methyl 2-deoxy-/3-L-ribopyrano- 

 side.2^^ The reactions involved in the glycal synthesis have been studied in 

 considerable detail, especially in the conversion of arabinose to arabinal 

 and then into 2-deoxyribose, and the overall yield of this particular con- 

 version has been doubled by recently introduced improvements, but it is 

 still very low.^" 



2-Deoxy-D-ribose has been prepared by using D-erythrose or its deriva- 

 tives as the initial material.^- ^ Sowden* used both 2,4-0-benzylidene-D- 

 erythrose and D-erythrose as initial materials. The former was condensed 

 with nitromethane and sodium methoxide to give a mixture of 3,5-0- 

 benzylidene-1-nitro-l-deoxy-D-ribitol and -D-arabitol; these were separated 

 by chloroform extraction. Hydrolysis and acetylation of the arabitol 

 derivative resulted in the formation of 2,3,4,5-tetra-O-acetyl-l-nitro-l- 

 deoxy-D-arabitol, which was converted into D-er?/^/iro-triacetoxy-l-nitro- 

 pentene by boiling under reflux in benzene solution with sodium bicarbon- 

 ate. Similarly this compound could be prepared from D-erythrose.^' ^ 

 Reduction of the pentene derivative, followed by treatment with sulfuric 

 acid yielded 2-deoxy-D-ribose. Sowden^ purified the product by forming 

 the benzylphenylhydrazone and regenerated the deoxypentose by treating 

 with either benzaldehyde or formaldehyde. Overend and co-workers® 

 favored formation of the aniline derivative ("anilide") as a means of isola- 

 tion and purification. Deanilination was effected by treatment with 0.5% 

 oxalic acid in aqueous solution, and 2-deoxy-D-ribose was obtained in 

 crystalline form. Good yields are obtained at all stages of this synthesis, 

 and for preparative purposes Sowden* claims that the isolation of inter- 

 mediates is unnecessary. The method would be a valuable one for the 

 preparation of 2-deoxy-D-ribose, if D-erythrose was obtainable in a pure 

 state in large quantities. 



Attempts have been made to convert methyl 2,3-anhydroriboside (XLIV) into 

 methyl 2-deoxy-D-riboside. The anhydro ring in XLIV can theoretically cleave in 

 two ways, giving rise to two different products, i.e., a 2-substituted derivative of 

 methyl D-arabinoside (XLV) and a 3-substituted derivative of methj^l D-xyloside 

 (XLVI). By using appropriate reagents for the cleavage it is possible to obtain de- 

 rivatives which can be converted directly to 2- or 3-deoxysugar derivatives. The 

 protection afforded by the glycosidic residue increases the possibility of improved 

 overall yields of the deoxysugars. 



Methyl 2,3-anhydro-/3-L-ribopyranoside was caused to react with sodium methyl- 

 mercaptide and thereafter the product was boiled under reflux with Raney nickel 

 to effect catalytic desulfurization of the mixture of methyl 2-methylthio-2-deoxy- 

 /3-L-arabinoside (XLV, R = SMe, D-isomer) and methyl 3-methylthio-3-deoxy-/3- 

 L-xyloside (XLVI, R = SMe, D-isomer). The main deo.xypentoside obtained was 



"1 R. E. Deriaz, W. G. Overend, M. Stacey, and L. F. Wiggins, J. Chem. Soc. 1949, 

 2836. 



