To a solution of 38.85 g of the compound (43) (112.8 mmol) in ethanol (200 ml)-THF (600 ml) was added diphenyldiazomethane (39 g, 201 mmol) little, by little over 30 min. at room temperature with stirring. After the reaction mixture was stirred for 1 h at room temperature, to the mixture was added diphenyldiazomethane (10 g, 51.5 mmol) and the resulting mixture was stirred for 1 h. To the reaction mixture was added acetic acid (0.1 ml) for quenching the excess reagent and the mixture was concentrated in vacuo. The residue (92 g) was crystallized by adding ether (1 L) to give 49.05 g (96.1%) of the compound (44).
