C-Nucleosides. 2. Synthesis of 3-(β-D-Ribofuranosyl)phthalimide

Article abstract of DOI:10.1021/jo00183a011

The synthesis of 3-(β-D-ribofuranosyl)phthalimide (19) from 2-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)furan (1) is described.One sequence started by aromatizing Diels-Alder-reaction adduct 2 to dimethyl 1-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)phthalate (3) with titanium tetrachloride-lithium aluminum hydride.Treatment of this with sodium hydroxide solution followed by dehydration with acetic anhydride and trifluoroacetic acid gave 3-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)phthalic anhydride (12).However, conversion of 12 into the phthalimide C-nucleoside was unsuccessful.The second sequence, which was brought to completion, made use of the adduct 1-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)-7-oxabicyclo<2.2.1>hept-5-ene-2,3-dicarboximide (17) as the starting material.Treatment of this with sulfuric acid in dichloromethane yielded phthalimide 18, which on deblocking with sodium methoxide gave the desired phthalimide C-nucleoside 19.