Under an argon atmosphere, 200 mg (0.65 mmol) of the compound from Example 214A, 49 μl of formic acid (1.3 mmol), 226 μl of triethylamine (1.63 mmol) and 38 mg of tetrakis(triphenylphosphine)palladium(0) (32 μmol) are dissolved in 2 ml degassed dioxan and stirred overnight at reflux temperature. To dissolve the precipitated solid, the reaction mixture is diluted with 20 ml of methanol after cooling to RT. The palladium catalyst is filtered off and the filtrate freed of the volatile components on the rotary evaporator. The residue is stirred with 5 ml acetonitrile and then suction-filtered. The solid is washed with acetonitrile and dried under high vacuum. It corresponds to the title compound with a purity of ca. 76% (130 mg, 57% of theory) and is used in the next reaction without further purification.
