5: 1.) <O> 6: 1.) n-Bu4NF, 2.) aq.AcOH / 1.) THF, 0 deg C 7: 68 percent / diethyl cyanophosphate / dimethylformamide / 0 °C 8: 86 percent / <O> 9: 69 percent / lithium hexamethyldisilazide / tetrahydrofuran / -78 - 0 °C 10: 1.) DDQ, 2.) aq.HCl / 1.) CH2Cl2, H2O 11: 64 percent / trifluoroacetic acid / 2.5 h / Ambient temperature View Scheme