1: 91 percent / 4-(N,N-dimethylamino)pyridine / acetonitrile / 0.25 h 2: 48 percent / sodium 2-ethylhexanoate, triphenylphosphine, tetrakis(triphenylphosphine)palldium / CH2Cl2; ethyl acetate / 1 h View Scheme

1: 91 percent / 4-(N,N-dimethylamino)pyridine / acetonitrile / 0.25 h 2: 48 percent / sodium 2-ethylhexanoate, triphenylphosphine, tetrakis(triphenylphosphine)palldium / CH2Cl2; ethyl acetate / 1 h 3: 1.) N-hydroxysuccinimide, dicyclohexylcarbodiimide (DCC) / 1.) CH2Cl2, 3 h, 2.) RT, 12 h 4: 1.) 85percent 3-chloroperoxybenzoic acid, 2.) NaBH3CN / 1.) acetone, 0 deg C, 30 min, 2.) acetic acid, 12 h 5: 95 percent / trifluoroacetc acid / CH2Cl2 / 1 h / Ambient temperature View Scheme