Regioselective, Stereoselective, and Conformationally Controlled Synthesis of (畏4-Tetraarylcyclobutadiene)(畏5-carbomethoxycyclopentadienyl)cobalt Metallocenes

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• 作者：Doyle J. Cassar ; Elisabeth Nagaradja ; David C. D. Butler ; Didier Villemin ; Christopher J. Richards
• 刊名：Organic Letters
• 出版年：2012
• 出版时间：February 3, 2012
• 年：2012
• 卷：14
• 期：3
• 页码：894-897
• 全文大小：289K
• 年卷期：v.14,no.3(February 3, 2012)
• ISSN：1523-7052

文摘

The Friedel鈥揅rafts reaction of (畏⁴-tetraphenylcyclobutadiene)(畏⁵-carbomethoxycyclopentadienyl)cobalt with acid chlorides/aluminum chloride resulted exclusively in para-phenyl acylation. Both monoacylated (1.1 equiv of RCOCl/AlCl₃) and tetraacylated products (>4 equiv of RCOCl/AlCl₃) were synthesized. Reaction of PhCC(o-RC₆H₄) (R = Me, i-Pr) with Na(C₅H₄CO₂Me) and CoCl(PPh₃)₃ gave predominantly (畏⁴-1,3-diaryl-2,4-diphenylcyclobutadiene)(畏⁵-carbomethoxycyclopentadienyl)cobalt metallocenes (1,3-[trans] vs 1,2-[cis] selectivity up to 6:1). Conformational control of Friedel鈥揅rafts reactions on the major isomers gave exclusively para-acylation of the unsubstituted phenyl groups.