1 research outputs found
Regioselective, Stereoselective, and Conformationally Controlled Synthesis of (η<sup>4</sup>-Tetraarylcyclobutadiene)(η<sup>5</sup>-carbomethoxycyclopentadienyl)cobalt Metallocenes
No full textThe Friedel–Crafts reaction of (η<sup>4</sup>-tetraphenylcyclobutadiene)(η<sup>5</sup>-carbomethoxycyclopentadienyl)cobalt with acid chlorides/aluminum chloride resulted exclusively in <i>para</i>-phenyl acylation. Both monoacylated (1.1 equiv of RCOCl/AlCl<sub>3</sub>) and tetraacylated products (>4 equiv of RCOCl/AlCl<sub>3</sub>) were synthesized. Reaction of PhCC(<i>o</i>-RC<sub>6</sub>H<sub>4</sub>) (R = Me, <i>i</i>-Pr) with Na(C<sub>5</sub>H<sub>4</sub>CO<sub>2</sub>Me) and CoCl(PPh<sub>3</sub>)<sub>3</sub> gave predominantly (η<sup>4</sup>-1,3-diaryl-2,4-diphenylcyclobutadiene)(η<sup>5</sup>-carbomethoxycyclopentadienyl)cobalt metallocenes (1,3-[<i>trans</i>] vs 1,2-[<i>cis</i>] selectivity up to 6:1). Conformational control of Friedel–Crafts reactions on the major isomers gave exclusively <i>para</i>-acylation of the unsubstituted phenyl groups
