To a solution of (S)-tert-butyl 3-((R)-2-(pent-4-enoyloxy)-2-phenylethylcarbamoyl)hex-5-enoate (470 mg, 1.13 mmol) in toluene (113 mL) was added Grubbs 2nd Generation catalyst (96 mg, 0.113 mmol) and the reaction mixture was heated to 65° C. Upon stirring 7 h with continued heating, TLC analysis indicated complete consumption of starting material. The reaction mixture was cooled to rt, diluted with degassed CH2Cl2 (11 ml) and Pb(OAc)4 (251 mg, 0.566 mmol) was added. The resulting mixture was stirred for 12 h at which point the mixture was passed through a short plug of silica then concentrated using rotary evaporation. The resulting purple solid was triturated with methanol to further remove ruthenium complexes. The off white solid that remained was purified using silica gel chromatography (MeOH/CH2Cl2 gradient) to yield 320 mg of desired product as a white solid in 73% yield. LRMS (M+Na)+: 410.4.
