Hydrogenation of 4-amino-1-(2,3,5-tri-O-benzyl-beta-D-arabinofuranosyl-1,3,5-triazin-2(1H)-one (I) in ethanolic hydrogen chloride and palladium on charcoal catalyst produces 4-amino-5,6-dihydro-1-(beta-D-arabinofuranosyl)-1,3,5-triazin-2(1H)-one hydrochloride (II). This is treated with bis (trimethylsilyl)trifluoroacetamide in acetonitrile solution to give the pentakis-trimethylsilyl derivative (III). Conversion to arabinosyl-5-azacytosine as the tetrakis-trimethylsilyl derivative (IV) is complete following 53 h of reflux of the silylation solution. The solution is then evaporated. The residual is boiled with methanol to remove the trimethylsilyl groups.

Hydrogenation of 4-amino-1-(2,3,5-tri-O-benzyl-beta-D-arabinofuranosyl-1,3,5-triazin-2(1H)-one (I) in ethanolic hydrogen chloride and palladium on charcoal catalyst produces 4-amino-5,6-dihydro-1-(beta-D-arabinofuranosyl)-1,3,5-triazin-2(1H)-one hydrochloride (II). This is treated with bis (trimethylsilyl)trifluoroacetamide in acetonitrile solution to give the pentakis-trimethylsilyl derivative (III). Conversion to arabinosyl-5-azacytosine as the tetrakis-trimethylsilyl derivative (IV) is complete following 53 h of reflux of the silylation solution. The solution is then evaporated. The residual is boiled with methanol to remove the trimethylsilyl groups.

Hydrogenation of 4-amino-1-(2,3,5-tri-O-benzyl-beta-D-arabinofuranosyl-1,3,5-triazin-2(1H)-one (I) in ethanolic hydrogen chloride and palladium on charcoal catalyst produces 4-amino-5,6-dihydro-1-(beta-D-arabinofuranosyl)-1,3,5-triazin-2(1H)-one hydrochloride (II). This is treated with bis (trimethylsilyl)trifluoroacetamide in acetonitrile solution to give the pentakis-trimethylsilyl derivative (III). Conversion to arabinosyl-5-azacytosine as the tetrakis-trimethylsilyl derivative (IV) is complete following 53 h of reflux of the silylation solution. The solution is then evaporated. The residual is boiled with methanol to remove the trimethylsilyl groups.