CHEMISTRY OF RIBOSE AND DEOXYRIBOSE 25 



■* H-C c( 



O H-C 



II 

 



XXII 



/«"-\ OMe 



\6 o-c^ "h 



/ 



\ 



H 



Sr++ 



O 



XXIII 



Levene and Tipson"" warmed D-rihose with methanolic hydrogen chloride and 

 obtained a syrupy methyl D-riboside (XVII). Methylation'^' of this glycoside fol- 

 lowed by acidic hydrolysis afforded crystalline tri-0-methylribose (XVIII). Oxida- 

 tion of XVIII with bromine yielded a tri-O-methylribonolactone (XIX) which hy- 

 drolyzed at a rate characteristic for 5(1, 5) -lactones. When XVIII was oxidized with 

 nitric acid (d., 1.42) and the product esterified, the diester XX obtained was devoid of 

 optical activity and was in fact methyl (-trimethoxyglutarate. It was apparent from 

 this sequence of reactions that XVII had a pyranose ring structure and that XVIII 

 was 2,3,4-tri-O-methyl-D-ribose. Soon after publication of the above work, the prep- 

 aration of a crystalline methyl D-riboside was reported by Minsaas.'^^ This glycoside 

 was obtained by treatment of D-ribose with 0.25% methanolic hydrogen chloride, and 

 it exhibited a different specific rotation from that reported by Levene and Tipson"* 

 for their syrupy product (XVII). The structure of this crystalline compound was 

 subsequently investigated by Jackson and Hudson'^* and it was proved to be methyl 

 ;8-D-ribopyranoside (XXI). For this work the glycoside was prepared by slight modi- 

 fication of Minsaas' procedure. Oxidation of the methyl riboside with periodic acid 

 or sodium metaperiodate resulted in the consumption of 2.02 moles of oxidant and 

 simultaneous formation of 1 mole of formic acid, thereby indicating that the material 

 was a glycopyranoside. The dialdehyde (XXII) also formed in this oxidation was 

 further oxidized with bromine to a dibasic acid, isolated as its strontium 

 salt (XXIII). The identity of XXIII with the strontium salts obtained when either 

 methyl /3-D-arabinopyranoside or methyl /3-D-xylopyranoside were subjected to the 

 same treatment'^' demonstrated that XXI had the/3-glycosidic configuration. Lattice 

 constants have been calculated'^" for this crystalline glycoside. The crystals were 

 rhombic and values obtained were a = 5.75 ± 0.02 A.;b = 6.39 db 0.02 A.; c = 19.90 

 ± 0.03 A. 



Barker'" has shown that the initial product of the action of methanol containing 

 1% hydrogen chloride on D-ribose is methyl D-ribofuranoside. The structure of this 

 glycoside was established by the classical method of methylation, hydrolysis and 

 oxidation to a lactone, which hydrolyzed at a rate characteristic of a 7 (1,4) -lactone. 



'38 P. A. Levene and R. S. Tipson, /. Biol. Chcm. 93, 623 (1931). 



'" J. Minsaas, Ann. 512, 286 (1934). 



'38 E. L. Jackson and C. S. Hudson, J. Am. Chem. Soc. 63, 1229 (1941). 



•" E. L. Jackson and C. S. Hudson, J. Am. Chem. Soc. 59, 994 (1937); 61, 1530 (1939). 



'"» H. Brackken, Kgl. Norske Videnskab. Selskabs Fork. 9 184 (1936). 



