II. CHEMISTRY 



199 



as active as L-ascorhic acid, the open-chain 2,3-diketo-L-gulonic acid (III) 

 is inactive."^ It is also ^'el•y Hkely that tlie unsaturated fi\'e-meinl)ered ring 

 must have both enohc hydroxyl groups, since the closely related 3-desoxy- 

 L-gulosaccharoascorbic acid" mentioned previously is inactive;"^ the syn- 



tabll: I 



Antiscorbutically Activk Substances 



(Tho fraction in paronthoses indicates the antiscorbutic activity on the basis 

 of unit activity for L-ascorbic acid.) 



CO- 



1 

 HO— C 



II 

 HO— C 



I 

 H— CO 



1 

 HO— C— H 



1 

 CH2OH 



L-Ascorbic acid 

 (vitamin C)"*- 



20. 33. 5-1, 104 



m.p. 192°, 

 [aU + 23° 

 (1) 



CO- 



I 

 HO— C 



II 

 HO— C 



H— CO-I 



H— C— OH 



HO— C— H 



CH, 



L-Fucoascorbic 

 acid" 



CO- 



i 

 HO— C 



HO— C 



H— CO-" 



HO— C— H 



CH3 



6-Desox}^-L- 



ascorbic 



acid "3 



m.p. 168°, 



Wn +37° 



i'A) 



CO^ 



I 

 HO— C 



HO— C 



H— CO 



I 

 HO— C— H 



HO— C— H 



I 

 CHs 



L-Rhamnoascorbic 

 acid*"- i"« 



CO- 



I 

 HO— C 



II 

 HO— C 



H— CO^ 



H- C— OH 



CH.OH 



D-Araboascorbic 



acid'"'' ^' **• •"•'■""' 



m.p. 174°, 



[aU - 17° 



i'Ao) 



CO-n 



I 

 HO— C 



II 

 HO— C 



I 

 H— CO-J 



HO— C— H 



HO— C— H 



CH2OH 



L-Glucoascorbic 



(^^0) 



m.p. 199°, [aJn + 28° m.p. 140°, [a]^ + 24' 

 (H) (Ho) 



CO 

 CO 



I 



CO 



I 



H— CO-" 



I 

 HO— C— H 



CH2OH 



Dehydro-L- 

 ascorbic acid 32. 33, 



127 



m.p. 225°, 



[aJD + 55° 



(1) 



co- 



HO— C 



no— c 



H— CO-J 

 HO— C— H 

 H— C— OH 



H— C— OH 



I 

 CH2OH 



D-Glucohepto- 

 ascorbic acid*'' '^ 



(Koo) 



"' D. Heslop and F. Smith, Unpublished results. 



