1: 88 percent / Ba(OH)2*8H2O / H2O / 1 h / Heating 2: 1.) LDA, 3.) TsOH / 1.) THF, 0 deg C, 1h, 2.) photooxygenation/ether, -78 deg C, 3.) THF, -78 deg C View Scheme

1: 50 percent / TEA / acetonitrile / 6 h / 55 °C 2: 88 percent / Ba(OH)2*8H2O / H2O / 1 h / Heating 3: 1.) LDA, 3.) TsOH / 1.) THF, 0 deg C, 1h, 2.) photooxygenation/ether, -78 deg C, 3.) THF, -78 deg C View Scheme

toluene-4-sulfonic acid; lithium diisopropyl amide 1.) THF, 0 deg C, 1h, 2.) photooxygenation/ether, -78 deg C, 3.) THF, -78 deg C; Yield given. Multistep reaction;