A CONVENIENT ROUTE TO D-APIO-BETA-D-FURAN OSYL AND 2'-DEOXYAPIO-BETA-D-FURANOSYL NUCLEOSIDES

2,3-O-Isopropylidene-D-apio-beta-D-furanose (1), available in 40% over all yield by modified literature procedures, is acylated regioselectiv ely to the new 3'-O-benzoyl-derivative 2. This is converted to the ano meric triacetates 4 (beta-4:alpha-4 = 1.8:1) by cleavage of the isopro pylidene protecting group from 2 followed by peracetylation. Reaction of compounds 4 with silylated nucleobases and subsequent deprotection gives the D-apio-beta-D-furanosyl nucleosides 8-10 in good yields. Reg ioselective hydrazinolysis of the protected nucleosides 5 and 6 afford s the 2'-hydroxy-derivatives 11 and 12, respectively, which are conver ted to the 2'-deoxyapio-beta-D-furanosyl nucleosides 17 and 18, respec tively, via deoxygenation of the corresponding thionocarbonates 13 and 14 with tris(trimethylsilyl)silane and subsequent deprotection. The 2 '-deoxyapio-beta-D-furanosyl cytosine 20 is prepared from the 2'-deoxy apio-beta-D-furanosyl uracil derivative 16.