An Efficient Route to Pentasubstituted Acylferrocenes

Abstract

A number of pentasubstituted acylferrocenes were selectively prepared from ferrous chloride, sodium acylcyclopentadienides, and the corresponding pentasubstituted lithium cyclopentadienides in good yields. The selectivity is governed by the different steric and electronic properties of the acylcyclopentadienides vs the pentasubstituted cyclopentadienides.

Multiple Acetylation of Pentaphenylferrocene – Synthesis and Asymmetric Reduction of 1‐Acetyl‐1′,2′,3′,4′,5′‐penta(para‐acetylphenyl)ferrocene

“…It has been suggested that pentaphenylferrocene is a less reactive substrate than ferrocene with respect to electrophilic substitution . This is supported by our observation that the 13 C NMR signal (CDCl 3 ) for the cyclopentadienyl group of ferrocene ( δ =68.3 ppm) is lower than the corresponding signal for pentaphenylferrocene ( δ =75.1 ppm).…”

“…as Cp* or Cp Φ ) leads to more selective catalysis . To this end the synthesis of 1′,2′,3′,4′,5′‐penta‐substituted acetylferrocenes have been described using ferrous chloride, sodium acetylcyclopentadienides, and the corresponding (Me, Et and Ph) penta‐substituted lithium cyclopentadienides . However, in addition to the desired compounds, a significant quantity of the bis ‐ketone 4 was produced.…”

“…sodium acetylcyclopentadienides, and the corresponding (Me, Et and Ph) penta-substituted lithium cyclopentadienides. [9] However, in addition to the desired compounds, a significant quantity of the bis-ketone 4 was produced. For 1-acetyl-1′,2′,3′,4′,5′-pentaphenylferrocene 3 the selectivity of the reaction was 89:11 with a 66 % yield of the desired ketone (Scheme 2).…”

“…Although a previous study showed that 1,2,3,4,5pentamethylferrocene could undergo Friedel-Crafts acetylation (albeit in 29 % yield), [10] application of the same conditions (AcCl/AlCl 3 ), and alternative conditions (Ac 2 O/BF 3 ), [11] to pentaphenylferrocene resulted in no reaction. [9] Conversely, work carried out by one of us has shown that the Friedel-Crafts reaction of pentaphenylferrocene 5 with ortho-chlorobenzoyl chloride resulted in the formation of the desired product in 91 % yield. [12] This methodology has been used for the synthesis of the pentaphenylferrocene congener of Phosferrox.…”

A Comparison of Phosphaferrocene and Phospharuthenocene Ligands in Rh+‐Catalysed Enamide Hydrogenation Reactions: Superior Performance of the Phospharuthenocene

“…Comparison of hydrogenation reactions of enamides using phosphametallocene-containing precatalysts 18 and 19. [66] " [13,67,68] 1-phenyl-3,4-dimethylphosphole, [69] [28,70] and [42,43] were obtained as described previously. Enamide substrates were prepared by standard methods; [71,72] rac-MetBuPHBH 3 was prepared from MePCl 2 and tBuMgCl in diethyl ether by Kuchen and Hägeles protocol, [73] followed by reduction with LiAlH 4 and treatment with BH 3 ·SMe 2 according to Imamotos general method; [74] tBu 2 PH·BH 3 was prepared similarly from tBu 2 PCl.…”