SYNTHESIS OF C-4 SUBSTITUTED PYRIMIDINE NUCLEOSIDE ANALOGS - PREPARATION OF SEVERAL 4-(2-OXOALKYLIDENE)-2(1H)-PYRIMIDINONE RIBONUCLEOSIDES

A series of 4-(1-alkynyl)-2(1H)-pyrimidinone ribonucleosides were synt hesized from the Pd-catalyzed coupling of terminal alkynes to the 4-ch loropyrimidin-2-one ribonucleoside (2). These compounds were hydrated, using three different methods, to afford the 4-(2-oxoalkylidene)-2(1H )-pyrimidinones. The 4-enol-pyrimidin-2-one structure of the title com pounds offers functional groups with the potential for Watson-Crick hy drogen bonding.