Preparation of d-galactofuranosyl nitromethanes: a revision and a new approach

Sodium methoxide-promoted methanolysis of 7-deoxy-7-nitro-l-glycero-l-galacto-heptitol peracetate rapidly and nearly quantitatively accumulates 7-deoxy-6-O-methyl-7-nitro-l-glycero-l-galacto-heptitol. The prolonged treatment then provides 76% of d-galactofuranosyl nitromethanes and finally results in the equilibrium of 77% of β-d-galactopyranosyl nitromethane and 7-9% of three other tautomeric d-galactosyl nitromethanes. Thermal treatment of 7-deoxy-7-nitro-l-glycero-l-galacto-heptitol in boiling water peaks at a 58% content of d-galactofuranosyl nitromethanes and ends in a similar equilibrium mixture of four d-galactosyl tautomers. The relevant kinetic parameters of the latter transformation are determined by a curve fitting using the nonlinear least-squares Marquardt-Levenberg algorithm.