Synthesis and antiviral activity of 4,6-disubstituted pyrimido[4,5-b]indole ribonucleosides.

A series of new pyrimido[4,5-b]indole ribonucleosides bearing phenyl or hetaryl group at position 4 has been prepared by selective Pd-catalyzed cross-coupling reactions of the corresponding protected 4,6-dichloropyrimido[4,5-b]indole ribonucleoside with (het)arylboronic acids or stannanes followed by deprotection. Further cross-couplings under harsher conditions and employing X-Phos ligand proceeded at the position 6 leading to 4,6-disubstituted pyrimido[4,5-b]indole ribonucleosides. Some of these compounds displayed antiviral activity against Dengue virus.