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

Abstract

The Friedel–Crafts acetylation of pentaphenylferrocene has been revisited using 1.1 equivalents of AcCl/AlCl3 in CH2Cl2 at room temperature leading to the synthesis of 1‐acetyl‐1′,2′,3′,4′,5′‐pentaphenylferrocene (78 % yield). Increased quantities of reagents and longer reaction times resulted in acetylation of the phenyl groups exclusively at the para‐position, this methodology culminating in the synthesis of 1‐acetyl‐1′,2′,3′,4′,5′‐penta(para‐acetylphenyl)ferrocene (32 % for a two step process). Subsequent asymmetric reduction of all six ketone functionalities with BH3·SMe2 catalysed by 60 mol‐% (S)‐CBS proceeded in 81 % yield to give (R,R,R,R,R,R)‐1‐(α‐hydroxyethyl)‐1′,2′,3′,4′,5′‐penta[para‐(α‐hydroxyethyl)phenyl]ferrocene, a highly functionalised enantiopure building block for the synthesis of ligands and materials.

(η4-Tetraphenylcyclobutadiene)-(η5-pentaphenylcyclopentadienyl)-cobalt

“…An updated search in SciFinder n now lists 503 entries for an "M-C 5 Ph 5 " search mask (accessed on 2 November 2022). The continuing interest in this substance class is based on two of its properties: bulkiness, which allows for stabilization of unusual geometries and oxidation states [2][3][4][5], and inherent "propeller chirality", which is supposed to induce stereoselectivity in catalytic reactions [6][7][8]. Whereas most publications are devoted either to the synthesis of compounds, owing to the unusual structures or physicochemical properties of the compounds, some studies were devoted to investigating their dynamical properties with respect to phenyl-and cyclopentadienyl rotation [9,10].…”

Central (S) to Central (M=Ir, Rh) to Planar (Metallocene, M=Fe, Ru) Chirality Transfer Using Sulfoxide‐Substituted Mesoionic Carbene Ligands: Synthesis of Bimetallic Planar Chiral Metallocenes

“…[3a] In this regard, recently,R ichards and co-workersr eported the preparation of diastereomerically enriched ferrocene-based planar chiral iridacycles by using enantiopure ferrocenyloxazolines. [14] For example, the cycloiridation of an enantiopure (S)valine-derived oxazoline resulted in the highly selectivef ormation of one of the four possible diastereomers. The stereoelectronic effect derived from the iron-iridiumi nteraction in ac oordinatively unsaturated intermediate was responsible for the high selectivity observed.…”