24.3 g of sodium hypophosphite×H2O and 4.02 g of Raney nickel were added to a solution of 6.08 g (13.42 mmol) of 8.1 in 200 ml of pyridine/acetic acid/water (2:1:1) at 0° C. and the reaction mixture was heated at 60° C. for 8 h. After cooling to room temperature and filtration, the reaction mixture was concentrated in vacuo, the residue was taken up in ethyl acetate and the ethyl acetate phase was extracted 2× with water, 2×with 10% strength citric acid solution, 2× with saturated NaHCO3 solution and with saturated sodium chloride solution. The organic phase was dried over magnesium sulfate and, after filtration, the solvent was removed in vacuo. 4.82 g (79%) of 8.2 were obtained.
