Iron(III) Triflimide as a Catalytic Substitute for Gold(I) in Hydroaddition Reactions to Unsaturated Carbon–Carbon Bonds

Abstract

In this work it is shown that iron(III) and gold(I) triflimide efficiently catalyze the hydroaddition of a wide array of nucleophiles including water, alcohols, thiols, amines, alkynes, and alkenes to multiple C-C bonds. The study of the catalytic activity and selectivity of iron(III), gold(I), and Brønsted triflimides has unveiled that iron(III) triflimide [Fe(NTf2)3] is a robust catalyst under heating conditions, whereas gold(I) triflimide, even stabilized by PPh3, readily decomposes at 80 °C and releases triflimidic acid (HNTf2) that can catalyze the corresponding reaction, as shown by in situ (19)F, (15)N, and (31)P NMR spectroscopy. The results presented here demonstrate that each of the two catalyst types has weaknesses and strengths and complement each other. Iron(III) triflimide can act as a substitute of gold(I) triflimide as a catalyst for hydroaddition reactions to unsaturated carbon-carbon bonds.

Radical‐Cation‐Induced Crossed [2+2] Cycloaddition of Electron‐Deficient Anetholes Initiated by Iron(III) Salt

“…Concentration and distillation to remove the solvent and 2 a under reduced pressure gave a crude mixture, which was purified by flash chromatography to provide pure 3 a in 81% yield (12.8 g). Since Fe(OTf) 3 is one of the simplest and strongest inorganic iron(III) oxidants, a decagram‐scale reaction in standard glassware (300 mL Erlenmeyer flask) could be successfully conducted.…”

Iron‐Catalysed Hydrofunctionalisation of Alkenes and Alkynes

“…The reactions were followed by using 19 F NMR and 15 N NMR spectroscopy to gain insight into the potential in situ hydrolysis of metal triflimides. [40] It was concluded that gold(I) triflimide was readily hydrolysed under the reaction conditions, whereas iron(III) triflimide was more robust. The formation of triflimidic acid was not identified during iron-catalysed hydration, hydrothiolation, hydroamination and hydroolefination reactions of alkynes and alkenes.…”

Iron(III)‐Catalyzed Hydration of Unactivated Internal Alkynes in Weak Acidic Medium, under Lewis Acid‐Assisted Brønsted Acid Catalysis

“…[8] While terminal alkynes can be selectively converted into the corresponding ketones, or aldehydes under specific ruthenium catalysts, [1] the transformations of internal alkynes poses additional concerns (Scheme 1). [3c,5a,b,c,g,7,8a,e, f,9] Specific attention has been given recently to these issues, [10] and the following are cases of significant achievements. [2b,d,e] The reaction scope is further hampered by difficult regioselectivity which is faced by most catalytic systems.…”

“…[2b,d,e] The reaction scope is further hampered by difficult regioselectivity which is faced by most catalytic systems. [3c,5a,b,c,g,7,8a,e, f,9] Specific attention has been given recently to these issues, [10] and the following are cases of significant achievements. Arylketones, which are the favored products when starting from asymmetric arylalkylalkynes, [2d,f] are also accessible under metal-free conditions in presence of directing hydroxyl [11] or carbonyl groups.…”