A combined X-ray and NMR study of borate esters of furanoidic cis-1,2-diols

Crystals of K[B(AnErytH(-2)2] x 2 H2O (AnEryt = 1,4-anhydroerythritol) form from aqueous alkaline solutions containing a double molar amount of diol over borate. The spiro-type monoanions are the main borate species in the mother liquors of crystallisation according to 11B and 13C NMR spectroscopy. Ribofuranosides form analogous borate esters using their 1,4-anhydroerythritol core. Crystals of Na[B(Me beta-D-Ribf 2,3H(-2))2] x 2 H2O were grown from alkaline methyl beta-D-ribofuranoside solutions that had attacked boron-containing Duran vessels. NMR spectra show closely resembling borate-ester speciation in solutions of diols with the 1,4-anhydroerythritol core--1,4-anhydroerythritol itself, methyl beta-D-ribofuranoside and guanosine.