HFIP‐Promoted Substitution in the Ferrocene Series: Smooth Approach towards Original Catalysts**

Abstract

Pseudo-benzylic substitution is an important reaction in the ferrocene series, especially to obtain ligands for catalysis. Herein, we described new reactions conditions, using fluorinated alcohols as both solvent and promoter, able to deliver iodoferrocene derivatives faster than using classical solvents. Various N, O, P and C-nucleophiles were found compatible with this transformation which occurs with full retention of stereochemistry. Original P,N-ligands were prepared by using iodine/ lithium exchange-chlorophoshine trapping sequences, and their properties were evaluated in Suzuki-Miyaura and Buchwald-Hartwig coupling as well as in ketone α-arylation reaction.

From ferrocene to decasubstituted enantiopure ferrocene-1,1′-disulfoxide derivatives

“…However, whether from the diol R P , R P -3 or the diacetate R P , R P -4 , no substitution occurred with phosphino- 99 or (phosphinomethyl)ferrocene 100 in acetic acid at room 101 or at reflux 96 temperature. Inspired by a previous study carried out in our group, 102 we also attempted to replace the two acetates with these phosphines (as well as amines and diamines; see ESI†) in hexafluoroisopropanol at 60 °C, but without success. The recovery of the starting material in all these reactions shows the very low reactivity of this sterically hindered diacetate in substitution reactions.…”

Exploring the boundaries of ferrocenesulfonyl fluoride chemistry

“…In 2017, Ball reported the reaction between 2,2,2-trifluoroethanol and 1-naphthalenesulfonyl fluoride in the presence of cesium carbonate. 49 As we recently shown that 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) can some-times behave as a weak nucleophile, 132 we attempted the reaction between 2 and this fluorinated alcohol. As one could have expected, reactions performed with cesium carbonate in acetonitrile at room temperature or sodium hydride in THF were sluggish (5% of desired product isolated 38d under the latter conditions).…”

Ferrocene derivatives with planar chirality and their enantioseparation by liquid‐phase techniques

“…In 2020, Kumar et al described the analytical enantioseparation of the N,N-diisopropyl-2iodoferroceneamide (131) on Chiralcel OD-3 with n-hexane/2-PrOH 98:2 v/v as mobile phase [193]. Later, Erb et al reported the analytical enantioseparation of the series of iodinated planar chiral ferrocenes 132a-e by using Chiralpak IA-3 and IC-3 as chiral columns under normal phase conditions (Table 6) [196]. It is worth noting that, given the hydrophobic character of iodine, the enantioseparation of some members of the series required the use of n-hexane-based mobile phases containing just 1% 2-PrOH.…”

“…Later, Erb et al. reported the analytical enantioseparation of the series of iodinated planar chiral ferrocenes 132a – e by using Chiralpak IA‐3 and IC‐3 as chiral columns under normal phase conditions (Table 6 ) [ 196 ]. It is worth noting that, given the hydrophobic character of iodine, the enantioseparation of some members of the series required the use of n ‐hexane‐based mobile phases containing just 1% 2‐PrOH.…”

“…Source: Adapted from Ref [45]. with permission TA B L E 6 High-performance liquid chromatography (HPLC) enantioseparation of iodinated planar chiral ferrocene 132a-e with Chiralpak IA-3 and IC-3 under normal phase conditions[196] Flow rate. b Retention time.…”