0.547 (TBAW), 0.630 (PhKC), 0.364 (BXLZ') 1.' The observed rotation of solutions of the pentose is negative, establishing the compound as D-ribose, rather than the L-isomer, which would give positive rotations. The pentose obtained from hydrolysis of nietllyl N,N'-dibenzoylneobiosaminide B also has becii shown to be D-ribose by a precisely analogous 1m-cedure, involving papergram color tests, Ri values, R-O--CJIsO(OIl)~~ ) -- C ' o J l ; O ( C j I ~ ) ~ I S H I ) ? mutarotation data and osazone form. The RC Pentose Diamiiiolierose (B iir Cj values are: ribose, 0.596 (TBAW), 0.308 (BXU'l; I a , !>, c hydrolysate pentose, 0.598 (TBAW), 0.80!) Ia, R = W Ib, R = CI-I, (BAW).g The mutarotation value of the isolated IC,R = Cl2H2-,S,0;(ileamine) pentose was - 17.1",that of D-ribose, determined We wish to express our appreciation to the Public simultaneously, - 1'7.6". The moss-like crystal Health Service for a research grant (Xo. E-127s) form of the osazone of the hydrolysate pentose, in support of this work, and to the Upjohn Com- m.p. i5So, was the same as that of ribosazone, 111.p. 159-162', very different from the needles of xylosupany for the generous gift of neomycin samples. zone, m.p. 162-164".10 DEPARTMENT OF CHEMISTRY KESSETIII,. RIXEHART, JR. Since the pentose from both neobiosamilles is A X D CHEMICAL ENGINEERISG PETERiV. I;.~ V O O I j T I V E R S I T Y O F ILLIXOIS ai^^^^^^^^ D. XRGOCDELIS D-ribose and neornycins B and C both contaiii LTRBAN.4, ILLISOIS ~ ~ S T R EM. A GIESRRECHT neamir~e,~ the formulas of neobiosainines B arid C , RECEIVED Jusc 24, 1957 of methyl neobiosaminides B and C, and of neomycins B and C may be represented by Ia. I b alld IC, respectively. The difference between the CHEMISTRY OF THE NEOMYCINS. 11. THE PENisomeric antibiotics presumably lies in the diariiinoTOSE MOIETY hexose moieties. The structures of the diaminoSir: hexoses, their position of linkage to ribose, the In the preceding Cominuiiication' it was shown position of ribose attachment to neamine and that the neobiosamine portion of both neomycin R questions of pyranose t's. furanose ring structure and neomycin C consists of a diaminohexosidopen- will, i t is hoped, be the subjects of future publicatose. We present here evidence that the pentose tions. moiety in both neobiosamines B and C is D-ribose. R--O-CsI-Ie( OIS)2--O-~-C6I-Ii0(OH)n ( N li2) D-Ribose Diaminohesuse (E or C) Methyl S,N'-dibenzoylneobiosaminide-C'was Ia,b, c hydrolyzed with dilute aqueous hydrochloric acid (neaiiiii:cj at reflux to give a mixture of products. Purifica- Ia, R = H ; Ib, R = CH8; IC,R = C12HL'i?;405 tion by partial precipitation, ion exchange resins We wish to express our appreciation to t h r b and chromatography gave a neutral, salt-free car- Public Health Service for a research grant (SO. bohydrate fraction, which was shown by color tests, E-1278) in support of this work, and to the 1.1)papergrams and rotation to be D-ribose. The john Company for the generous gift o f neoniyciii compound is an aldopentose' since its papergram samples. We also wish to thank Professor TV. gives an orange-brown color when developed with Wood for helpful advice and suggestions. p-dimethylaminoaniline and trichloroacetic acid5 (8) T B A W is feri-butyl alcohol, acetic acid. water, 2 . 1 - 1: I'hKC is and a red color when developed with aniline acid phenol -4- 1% ammonia + hydrogen cyanide (trace): R A W is ??-butyl phthalate,6 but no gray-green color (indicative of a alcohol :acetic acid: water: 4 : 1: 5 . ( 9 ) Slight variations in absn1ute values tietween these IZr's a i i d ketopentose and found in model papergrams of rithose above are d u e t o operator a n d room temgeraturc differences. bulose and xylulose) when developed with or- Each series is, however, self-consistent and valucs within a series nere cinol and trichloroacetic acid.: In simultaneous obtained in a single chromatogram. (10) W. Z . Hassid and R. RI. hIcCready, Ii4rl. L:)!g. C h z t n . , . A l ! , d papergrams (at least two chromatograms in each solvent system) with the four aldopentoses and two Ed., 14, 683 (1942). ~ E S N E I . 1 1L. k S K I I A R T , J R . ketopentoses, the material was shown to give Ri PETERm'.K. i V o o values quite close to those of ribose, but very dif!lI.E.XASDt
