Flaming Pointer
Step 1: 37 to S8 Benzyl ester 37 (0.022 g, 0.04 mmol, 1.0 equiv) was dissolved in methanol (2 mL) at 23°C. AcOH (0.015 mL, 0.020 mmol, 5.0 equiv) was added to this solution, followed by 20% Pd(OH)2/C (0.016 g). The solution was then stirred under an atmosphere of H2 (1 atm) for 3 hours. After, the reaction mixture was filtered through celite and concentrated in vacuo to yield carboxylic acid S8 (0.018 g, 99%) in the form of a colorless oil. Step 2: S8 to 39 Carboxylic acid S8 (0.017 g, 0.034 mmol, 1.0 equiv) was dissolved in THF (0.20 mL). The ylide derived from triphenyl phosphonium bromide (0.34 mL of a 0.45M solution in THF, 0.15 mmol, 4.5 equiv) was added to this solution at 50°C. The mixture was then stirred at 50°C for 18 hours. After, the mixture was quenched with AcOH (0.020 mL), diluted with DCM (3 mL) and concentrated in vacuo. The residue was purified using silica gel flash chromatography (9:1 CH2Cl2/CH3OH then 4:1 CH2Cl2/CH3OH) to yield alkene 39 (0.015 g, 72%) in the form of a colorless oil.