SYNTHESIS OF CARBOCYCLIC NUCLEOSIDES, (-)-NEPLANOCIN-A AND ITS ANALOGS

The tide compounds, 'R)-4'-hydroxymethylcyclopent-4'-en-1'-yl)purines, were synthesized via chemoselective S(N)2 substitution (by the Mitsun obu reaction) of the sec-allylic hydroxy group of a protected carbofur anose synthon for purines at the N-9 position. The carbofuranose synth on, (3S,4S,8R)-1-benzyloxymethyl-3-hydroxy-6, 6-dimethyl-5,7-dioxabicy clo[3.3.0]oct-1-ene, was prepared from 6,6-dimethyl-5,7-dioxabicyclo[3 .3.0]oct-2-en-1-one via stereospecific chloromethylation of the carbon yl group followed by five step conversion.