1.1: 46 percent / (i-Pr)2NH / PdCl2(PPh3)2; CuI / tetrahydrofuran 2.1: aq. KOH / methanol / 12 h 3.1: 251 mg / [2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium]*BF4; (i-Pr)2NEt / CH2Cl2 / 12 h 4.1: BuLi / hexane; tetrahydrofuran / 0.25 h / -78 °C 4.2: 78 percent / hexane; tetrahydrofuran / -78 - 20 °C 5.1: 67 mg / acetonitrile / 2 h / Irradiation View Scheme

1.1: aq. KOH / methanol / 12 h 2.1: 251 mg / [2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium]*BF4; (i-Pr)2NEt / CH2Cl2 / 12 h 3.1: BuLi / hexane; tetrahydrofuran / 0.25 h / -78 °C 3.2: 78 percent / hexane; tetrahydrofuran / -78 - 20 °C 4.1: 67 mg / acetonitrile / 2 h / Irradiation View Scheme

1.1: BuLi / hexane; tetrahydrofuran / 0.25 h / -78 °C 1.2: 78 percent / hexane; tetrahydrofuran / -78 - 20 °C 2.1: 67 mg / acetonitrile / 2 h / Irradiation View Scheme

in acetonitrile photo-dehydro-Diels-Alder reaction; 2 h; Irradiation;

Yield given. Multistep reaction;