Iron(III)‐Catalyzed Halogenations by Substitution of Sulfonate Esters

Abstract

A novel halogenation reaction from sulfonates catalyzed by ironA C H T U N G T R E N N U N G (III) is described. The reaction can be performed as a stoichiometric or a catalytic version. This reaction provides a convenient strategy for the efficient access to structurally diverse secondary chlorides, bromides and iodides. The stereochemical course of the reaction is governed by the substrate and the experimental conditions. Secondary alcohols modified as quisylates or pysylates are substantially more reactive. Aliphatic quisylates proceed with overall inversion of configuration under catalytic conditions. Chemoselectivity in bismesylates was observed in favour of the secondary mesylate. Additionally, based on the experimental results, a possible catalytic cycle for the halogenation has been proposed.

Iron Catalysis in Organic Synthesis

“…A typical example is presented in Scheme 57. 129 In general, 8-quinolinesulfonates and 2-pyridinesulfonates turned out to be more reactive than mesylates. The stereochemical outcome of the reaction varied depending on the substrate and the reaction conditions.…”

Aryl Radical‐Mediated Alkenylation of Alkyl Halides

“…Starting from diastereomerically pure menthyl iodide 1i, the corresponding olefin 3i was obtained in good yield and high diastereocontrol, with the configuration as shown. A 7 : 3 diastereomeric mixture of 3β-iodo-5αcholestane 1j, [31] under similar conditions led to olefin 3j as a 75 : 25 mixture of diastereoisomers. Finally, the formation of hexylphenylsulfone (5), along with the desired product 3k, was also observed when starting from hexyl iodide (1k).…”

Rearrangement in Stereoretentive Syntheses of Menthyl Chloride from Menthol: Insight into Competing Reaction Pathways through Component Quantification Analysis

“…The absence of rearrangement products in that reaction was emphasized and taken as evidence against the intermediacy of a free carbenium ion in the reaction mechanism . In related work, menthyl sulfonates were converted to 2 by stoichiometric amounts of Lewis acids (TiCl 4 , FeCl 3 ), or by Me 3 SiCl in the presence of the catalyst Fe(acac) 3 …”