A mixture of Intermediate 1 (52.8 g, 190.49 mmol), triphenylphosphine (4.99 g, 19.05 mmol), zinc cyanide (22.37 g, 190.49 mmol) and dry acetonitrile (360 mL) was introduced in a pressure tube and was degassed with nitrogen for 5 min. Tetrakis(triphenylphosphine)palladium (11 g, 9.52 mmol) was added and the mixture was further degassed for 5 min. The tube was sealed and the reaction mixture was stirred at 140° C. for 3 h. The suspension was evaporated and taken up in water/DCM. The combined organic layer was separated, filtered on a plug of diatomaceous earth, dried on MgSO4, filtered off, and evaporated. The residue was purified on an 800 g EasyVarioPrep (Merck) column (eluent: DCM). The desired fractions were concentrated in vacuo and dried in a vacuum oven at 50° C. overnight, yielding 25.6 g (60%) of Intermediate 2 as a yellow solid.
