Promising results were obtained by chemical ionization desorption mass spectrometry for a series of original pyridinium nucleoside salts, together with some purine and pyrimidine nucleo(t)sides. They were recorded using ammonia as reagent gas and tungsten wires. Principal ions correspond to protonated or cationized ([NH,I+) forms of the molecular ion or the free base depending upon the compound under investigation.

This paper reports the purification and separation of several tri-0-benzoyl-D-ribofuranose derivates (2,3,4,5) by counter current distribution. A new product l-O-Ethyl-2,3,5-tri-benzoylp-D-ribofuranose ( 5 ) has been isolated. The purity of all these products was tested by T.L.C. The N.M.R. spectra are discussed.INTRODUCTION :

Die Titelverbindung (III) wird durch Umsetzung vom Nucleotid (II) mit dem Anhydrid (I) synthetisiert.

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+ 1-3, a total synthesis of B-NAD' analogues substituted on both 3-and 5-positions of the pyridinium ring has been planned. To get hold of such a comnlex molecule, considerable efforts were made to obtain the 3,s-disubstituted avridinium nucleotiaes stereosnecifically and in goodWe now wish to renort the svnthesis of 3-Ac-5-Me-PvrAD+(z). This comnound was formed by counling 3-acetvl-5-methvlpvridinium nucleotide