Synthesis of 1,3-Dl-O-Acetyl-5-O-Benzoyl-2-O -(O-Carboran-1-Ylmethyl)- D-Ribofuranose. A General Precursor for the Preparation of Carborane-Containing Nucleosides for Boron Neutron Capture Therapy

Abstract
An eight-step synthesis of 1,3-di-O-acetyl-5-O-benzoyl-2-O-(o-carboran-1-ylmethyl)-D-ribofuranose 9 was carried out from 1,2:5,6-O-isopropylidene-α-D-allofuanose 1. Condensation of 9 with trimethylsilyl protected uracil in the presence of trimethylsilyl trifluoro-methanesulfonate, and subsequent deblocking of the resulting 1-[3-O-acetyl-5-O-benzoyl-2-O-(o-carboran-1-ylmethyl)-D-ribofuranosyl]uracil 10 (>95& β-configuration) by alkaline hydrolysis, yielded 1-[2-O-(o-carboran-1-ylmethyl)-β-D-ribofuranosyl]uracil 11.