To a solution of D9 (0.065 g, 0.196 mmol) in DCM (2.5 ml) were added morpholine (0.026 g, 0.294 mmol) and sodium triacetoxy-borohydride (0.062 mg, 0.294 mmol). The resulting mixture was stirred at r.t. for 1 day. The reaction mixture was washed with H2O, dried (MgSO4) and concentrated in vacuo. The crude product thus obtained was purified by column chromatography (silica gel; DCM/MeOH up to 3% as eluent). The desired fractions were collected and concentrated in vacuo to yield final compound E11 (0.04 g, 51%) as a white solid.
