SYNTHESIS OF 3'-(N-ACETYLPIPERAZINO)-2',3'-DIDEOXY-D-RIBO-HEXOFURANOSYL AND 3'-(N-ACETYLPIPERAZINO)-2',3'-DIDEOXY-D-RIBO-HEXOFURANOSYL-D-ERYTHRO-PENTOFURANOSYL THYMINE NUCLEOSIDES

Michael-type addition of N-acetylpiperazine to the cc,P-unsaturated hexose aldehyde 1 in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene gave an anomeric mixture of 3-(N-acetylpiperazino)-2,3-dideoxy-D-ribo-hexofuranoses, which was acetylated to give the tri-O-acetyl derivative 2. Reaction of 2 with silylated thymine 5 using trimethylsilyl trifluoromethanesulfonate as catalyst gave the hexofuranose nucleosides 6 and 7. The pure anomers were deprotected using a saturated solution of NH, in dry MeOH affording 8 and 9. Conversion of 8 and 9 into the corresponding pentofuranose nucleosides 10 and 11 was accomplished by periodate oxidative cleavage and subsequent reduction.