L. Denapoli et al., 6-CHLOROXANTHOSINE, A USEFUL INTERMEDIATE FOR THE EFFICIENT SYNTHESESOF [6-N-15]-ISOGUANOSINE, ISOINOSINE AND OTHER PURINE NUCLEOSIDE ANALOGS, Nucleosides & nucleotides, 16(1-2), 1997, pp. 183-191
6-Chloroxanthosine 1, when activated towards nucleophilic displacement
at the 6-C position by conversion into the corresponding 3-N-(2,4-din
itrophenyl) derivative 4, reacted with aq. (NH3)-N-15 to afford [6-N-1
5]-isoguanosine 3b in 81% overall yield. Catalytic hydrogenation (Pd/C
) of 1 led in 60% yield to isoinosine 8; alternatively, this could be
obtained in 88% overall yield through alkaline hydrolysis of triphenyl
phosphonium salt 6, synthesized from 1 by reaction with PPh(3). The re
activity of 1 was further explored by treating it with primary and sec
ondary amines: the 6-N propylamino and the 6-N piperidinyl derivatives
(5a and 5b, respectively) could thus both be prepared in more than 90
% yield.