HOTf-catalyzed intermolecular hydroamination reactions of alkenes and alkynes with anilines

Abstract

Herein, the intermolecular hydroamination of alkenes and alkynes with anilines catalyzed by HOTf under mild conditions has been developed.This reaction provides one of the simplest alkene and alkyne addition methods and is an alternative to metal-catalyzed reactions. At the same time, the intramolecular hydroamination of alkynes with anilines proceeds smoothly to obtain quinolines. We found that this strategy is efficient in building complex structures from simple starting materials in an environmentally benign fashion.

Continuous-Flow Synthesis of β-Amino Acid Esters by Lipase-Catalyzed Michael Addition of Aromatic Amines

“…Michael addition is one of the simplest and most effective strategies to prepare β-amino acid esters. Recently, Ahmed has reported the Michael addition of aromatic amines mediated by KOtBu [10]; HOTf (trifluoromethylsulfonic acid) was also used to catalyze the Michael addition of aromatic amines, and good yields were obtained within 4 h [11]. However, the use of acids and alkalis has brought challenges to the environment.…”

Cobalt-Catalyzed Hydroarylations and Hydroaminations of Alkenes in Tunable Aryl Alkyl Ionic Liquids

“…Similarly, hydroaminations and hydroarylations are among the most sought-after reactions because of their high atom economy. − In particular, we were interested in the intermolecular addition of anilines to olefins (Scheme ). Common approaches for this reaction include the use of ligand-modulated late transition metals, − strong Brønsted acids, − and earth-abundant metals. − There are some reports on the use of ionic liquids in this type of reaction, − especially for the reaction of the more reactive acetylenes and activated olefins or for reactions (co)­catalyzed by Brønsted acids. − …”

Copper-Catalyzed Intermolecular Hydroamination of Internal Alkynes with Anilines and Amines

“…We further conducted the Cu­(OTf)-catalyzed reaction at a lower temperature (40 °C) by increasing the amount of Cu­(OTf) to 10 mol % in dioxane or THF and succeeded in obtaining the product 4aa without any reduced yield (entries 14 and 15). Unfortunately, the reaction at room temperature resulted in a lower yield (78%) (entry 16), and this result indicated that the reaction requires 40 °C to provide quantitative yields in 12 h. To avoid the possibility that TfOH, which might be produced from Cu­(OTf) in situ, catalyzed the hydroamination reaction, we carried out the reaction of 1a with 2a in the presence of a catalytic amount of TfOH (1 or 10 mol %) and confirmed that not even a trace amount of the product was formed (entry 17). Furthermore, we examined the Cu­(OTf) 2 -catalyzed reaction in other solvents, such as CH 3 CN or toluene, and concluded that THF is the best solvent for this hydroamination reaction (entries 18 and 19).…”