Mass spectrometry of some N-acyldaunosamine derivatives.
Abstract The principal modes of fragmentation subsequent to electron impact of some N -acyl derivatives of daunosamine, the glycoside moiety of the antitumour antibiotics daunomycin and adriamycin, have been studied by using specifically deuterated derivatives and high-resolution measurements. In particular, the elimination of MeOH from methyl β-daunosaminides is shown to occur extensively and stereo-specifically, and involves HO-4. The splitting of the moieties C-1-C-2 and C-5-O-5 affords the fragments D 2 , D ′ 2 , and D ′′ 2 , which are among the most abundant.
Synthesis of 3-amino-2,3,6-trideoxy-D-ribo-hexose hydrochloride.
The title sugar, the 5-epimer of daunosamine, was prepared in a sequence of high-yielding steps from methyl alpha-D-mannopyranoside (1). Conversion of 1 into methyl 3-acetamido-4-O-benzoyl-6-bromo-2,3,6-trideoxy-alpha-D-ribo-hexopyranoside (2), followed by reduction with hydrogen and Raney nickel, gave the 4-benzoate (3) of methyl 3-acetamido-2,3,6-trideoxy-alpha-D-ribo-hexopyranoside (4). Saponification of 3 gave 4 as an oil that gave a crystalline 4-acetate (8). N-Deacetylation of 4 was effected with barium hydroxide, and the resultant glycoside was hydrolyzed to give 3-amino-2,3,6-trideoxy-D-ribo-hexose hydrochloride (7). The 3-benzamido analogue (5) of 4 was prepared from 4 by N-deacetylation and subsequent benzoylation, and hydrolysis of 5 gave crystalline 3-benzamido-2,3,6-trideoxy-D-ribo-hexose (6). The crystalline 3-acetamido analogue (9) of 6 was obtained by acid hydrolysis of the glycoside 4.
Spectrographie de masse en srie du bornane I: Bornanes monosubstitus
Dans le cadre d'une etude sur le mecanisme de fragmentation de bornanes 2 et 3 monosubstitues, les auteurs ont interprete les spectres de masse d'un certain nombre de cetones, oximes, alcools, amines et derives N-methyles. Il est a noter que la fragmentation est differente selon la position des substituants, et que la rupture en α du substituant porteur de la charge est preponderante. De plus, la rupture de cette liaison se fait du cote du carbone qui est le plus substitue. Enfin, les spectres de masse permettent de differencier sans ambiguite la position 2 de la position 3. 
 
 
 
A study has been made of the fragmentation of 2- and 3-monosubstituted bornanes. Ketones, oximes, alcohols, amines and their N-methyl derivatives were examined. Different fragmentations were compared according to the 2- or 3-position of the substituents. The results show the importance of cleavage α to the substituent bearing the charge. The α bond cleaved is that bond directed to the carbon atom with the greater degree of substitution. These results allow one to differentiate, by mass spectroscopy, the 2- and the 3-positions in the bornane skeleton.