52 W. G. OVEREND AND M. STAGEY 



methyl 2-0-p-toluenesulfonyl(or methanesulfonyl)-i3-L-arabinoside. The 

 complex mixture of products contained some methyl 2-deoxy-/3-L-riboside. 

 Since derivatives of 3-deoxy-D-glucose became available, efforts have been 

 directed towards the preparation of 2-deoxy-D-ribose from this deoxyhexose 

 and from either calcium or barium 3-deoxy-D-gluconate. It has been shown 

 in the writers' laboratory that when the modification of Ruff's method that 

 was introduced by Hockett and Hudson^- is employed, calcium 3-deoxy-D- 

 gluconate can be degraded to 2-deoxy-D-ribose. Richards^** has demon- 

 strated that the application of Ruff's method of degradation to calcium 

 c^ex^ro-metasaccharinate^*^ under the conditions described by Fletcher 

 et al."^^^ affords the 2-deoxy-D-ribose in satisfactory yield. Furthermore, it 

 is not necessary to separate a- from /3-metasaccharinic acid, since a mixture 

 of the two is equally effective. Hough^*^ has outlined a novel method for 

 the synthesis of 2-deoxy-D-ribose. An excess of allylmagnesium bromide was 

 allowed to react with 2,3-isopropylidene-D-glyceraldehyde and, after de- 

 composition of the resultant complex, syrupy 5,6-isopropylidene-l- 

 hexene-4 , 5 , 6-triol (XLVII) was obtained in excellent yield. This reaction 

 results in the formation of a new asymmetric center* at carbon atom 4. On 

 treatment of XLVII with a solution of hydrogen peroxide in tert-huty\ 

 alcohol containing a little osmium tetroxide as catalyst, the double bond is 

 hydroxylated and a new center of asymmetry is produced at carbon atom 2. 

 From the mixture of products a fraction containing 5 , 6-0-isopropylidene- 

 3-deoxyhexitols was obtained. Oxidation of this fraction with sodium 



CH2 



II 

 CH 



CH2 



*CHOH 



H— C— O CH3 



\ / 

 C 



/ \ 

 H2C— O CH3 



XLVII 



metaperiodate destroyed the asymmetric center at carbon atom 2 and gave 

 a mixture of 4 , 5-isopropylidene-2-deoxypentoses which on acidic hydrolysis 



28* G. N. Richards, Chemistry & Industry 1953, 1035. 

 28^ J. U. Nef, Ann. 376, 1 (1910). 



286 H. G. Fletcher, Jr., H. W. Diehl, and C. S. Hudson, /. Am. Chem. Soc. 72, 4546 

 (1950). 



287 L. Hough, Chemistry & Industry 1951, 406; J. Chem. Soc. 1953, 3066. 



