Iron-Catalyzed Regio Research Articles

Iron-catalyzed regio- and stereoselective substitution of 2,4-alkadienyl carboxylates with aryl Grignard reagents

Treatment of 2,4-alkadienyl carboxylates with an aryl Grignard reagent in the presence of a catalytic amount of FeCl2 affords diene derivatives in high yields with regio- and cis-stereoselectivity. Additionally, optically active 2,4-alkadienyl carboxylates afford the corresponding optically active dienes in high yields and with excellent degrees of chiral transfer. More importantly, the absolute structures of both starting material and product clarified the stereochemical pathway.

Iron-Catalyzed Regio- and Stereoselective C-H Alkenylation of Pivalophenone Derivatives with Unsymmetric Internal Alkynes.

Here we report an ortho-C-H alkenylation of aromatic ketones with unsymmetric internal alkynes catalyzed by an iron phosphine complex, Fe(PMe3)4. The use of a catalytic amount of PtBu3 as an additive was found to improve the product yields. The alkenylation proceeds regio- and stereoselectively to give the corresponding styrene derivatives.

Iron-Catalyzed Synthesis of (E)-β-Vinylsilanes via a Regio- and Stereoselective Hydrosilylation from Terminal Alkynes

A concise strategy for the synthesis of vinylsilanes from an iron-catalyzed regio- and stereoselective hydrosilylation of terminal alkynes has been developed. The catalyst and reagents are commercially available and easy to handle, providing a simple and practical method for iron-catalyzed anti-Markovnikov hydrosilylation with a good functional group tolerance.

Synthesis of cis-1,2-dichlorovinylsulfones via Fe-catalyzed regio- and stereoselective addition of sulfonyl chlorides to aromatic chloroalkynes

An iron-catalyzed regio- and stereoselective chlorosulfonylation of aryl chloroalkynes has been described, producing cis-1,2-dichlorovinylsulfones in satisfactory yields with good to excellent stereoselectivity (Z/E up to 95:5). A variety of functional groups such as F, NO2, Cl, Br, OMe, and t-Bu are found to be compatible under the reaction conditions.

Iron-Catalyzed Regio- and Stereoselective Chlorosulfonylation of Terminal Alkynes with Aromatic Sulfonyl Chlorides

Terminal alkynes react with aromatic sulfonyl chlorides in the presence of an iron(II) catalyst and a phosphine ligand to give (E)-β-chlorovinylsulfones with 100% regio- and stereoselectivity. Various functional groups, such as chloride, bromide, iodide, nitro, ketone, and aldehyde, are tolerated under the reaction conditions. Addition of tosyl chloride to a 1,6-enyne followed by radical 5-exo-trig cyclization gave an exocyclic alkenylsulfone.

Iron-Catalyzed Regio- and Stereoselective Substitution of γ,δ-Epoxy-α,β-unsaturated Esters and Amides with Grignard Reagents

When gamma,delta-epoxy-alpha,beta-unsaturated esters or amides were treated with 2 equiv of Grignard reagents in the presence of 10-24 mol % FeCl(2), regio- and stereoselective substitution of the epoxide moiety with the Grignard reagent occurred to give exclusively delta-hydroxy-gamma-alkyl or aryl-alpha,beta-unsaturated esters or amides in good yields.

Iron-catalyzed regio- and stereoselective addition of acid chlorides to alkynes

An iron-catalyzed regio- and stereoselective addition of acid chlorides to alkynes has been described. The reaction utilizes an inexpensive iron catalyst system and it is suitable for the formation of a variety of bifunctional molecules. This is an inexpensive, regio-, stereoselective and atom-economical approach to beta-chloro-alpha,beta-unsaturated ketones from simple and readily available starting materials.

Iron-Catalyzed Regio- and Stereoselective Ring Opening of [2.2.1]- and [3.2.1]Oxabicyclic Alkenes with a Grignard Reagent.

Arylative and alkenylative ring-opening reactions of a [2.2.1]- or [3.2.1]oxabicyclic alkene with a Grignard reagent take place in the presence of a catalytic amount of iron(III) chloride and a sto...

Iron-catalyzed regio- and stereoselective ring opening of [2.2.1]- and [3.2.1]oxabicyclic alkenes with a Grignard reagent.

[reaction: see text] Arylative and alkenylative ring-opening reactions of a [2.2.1]- or [3.2.1]oxabicyclic alkene with a Grignard reagent take place in the presence of a catalytic amount of iron(III) chloride and a stoichiometric amount of TMEDA to produce a highly substituted 3-cyclohexen-1-ol or 3-cyclohepten-1-ol in good yield with high regio- and stereoselectivity.

Iron-Catalyzed Regio- and Stereoselective Carbolithiation of Alkynes.

Butylation problems ironed out: 3-Pentynyl ethers react with butyllithium at -20°C in toluene, upon addition of a catalytic amount of a cheap iron(III) salt, to afford (E)-4-methyl-3-octenyl ethers in high yields. Stereochemically defined tetrasubstituted alkenes were also obtained by the subsequent addition of electrophiles (E+ , see scheme; acac = acetylacetonate, Bn=benzyl).

Iron-Catalyzed Regio- and Stereoselective Carbolithiation of Alkynes

Katalytische Mengen günstiger Eisen(III)-Salze lassen bei der Reaktion von 3-Pentinylethern mit Butyllithium bei −20°C in Toluol die (E)-4-Methyl-3-octenylether in hohen Ausbeuten und ohne die sonst zu erwartenden Nebenreaktionen entstehen. Eine anschließende Addition von Elektrophilen (E+, siehe Schema; acac = Acetylacetonat) liefert stereochemisch definierte tetrasubstituierte Alkene.