Synthesis of(14C6-3,4,7,8,11,12)-(1E,5E,9E)-cyclododeca-1,5,9-triene

Trimerization of butadiene in the presence of Ni(0) affords (IE,5E,9E)-cyclododeca- 1,5,9-triene 1 (ttt-CDT), (1E,5E,9Z)-cyclododeca-1,5,9-triene 2 (ttc-CDT), and other isomers/ oligomers. After optimization of reaction [C-14(6) -3,4,7,8,11,12]-ttt-CDT 1 was synthesized efficiently either by homogenous or heterogeneous conditions, Ni(0) catalytic trimerization of [1,4(-14)C(2)]butadiene 10, in 60-82% yield. Depending on the exact reaction conditions employed, the yields and ratio of 1/2 ranged from (59-90%) / (41-10%). The all-trans isomer was conveniently isolated Via Ag+-mediated reversed-phase HPLC. The important intermediate [1,4-C-14(2)]-1,3-butadiene 10 was prepared from potassium [C-14]cyanide and 1,2-dibromoethane 3 as starting materials, in seven steps with a 57% yield. The total radioactive yield of [C-14(6)-3,4,7,8,11,12]-ttt-CDT 1 is 30% from [C-14]KCN. Copyright (C) 2007 John Wiley & Sons, Ltd.