... entry 4). With potassium tert-butoxide, triazolium salt 11 provided 16% yield (entry 5), whereas lithium hexamethyldisilazide at 56 °C in toluene afforded a 9% yield of 6 (entry 6). Diluting a 2.5:1 mixture of methylene chloride/tert-butanol from 0.01 to 0.0025 M and utilizing DBU ...