Regioselective Preferential Nucleophilic Addition of N-Heterocycles onto Haloarylalkynes over N-Arylation of Aryl Halides

Abstract

The study of preferential addition of heterocyclic amines onto halo-substituted arylalkynes over N-arylation under various catalytic conditions is described. The present work supports and confirms the mechanistic pathway of our recent work on the tandem synthesis of indolo- and pyrrolo-[2,1-a]isoquinolines via hydroamination followed by oxidative addition and not vice versa.

Gold nanoparticles supported on functionalized silica as catalysts for alkyne hydroamination: A chemico-physical insight

“…As a matter of fact, the addition of an amine to a C-C unsaturated bond is kinetically hampered by the electron repulsion between the multiple bond π system and the electron density located on nitrogen, resulting in a high activation barrier [10]. Non-catalytic hydroaminations involve the use of strong acids to protonate the C−C multiple bond, facilitating the amine attack [11][12] [13], or strong bases to generate strongly nucleophilic amido species, which react more easily with C−C moieties [14][15] [16]. As a consequence, a great deal of efforts have been recently focused on the development of efficient metal-based catalysts for this type of reactions [10] [17] [18] [19].…”

Hydroamination of terminal alkynes with secondary amines catalyzed by copper: regioselective access to amines

“…11 Verma et al described the anti-Markovnikov addition of N-heterocycles with internal alkynes catalysed by Cu(I)/benzotriazole system. 12 A simple CuCl catalyst has been used for the Markovnikov hydroamination of terminal alkynes with anilines derivatives. 13 Recently hydroamination of alkynes with electrophilic amines catalysed by copper/ligand systems were described.…”

Metal‐Catalyzed Divergent Synthetic Methods for Pyrrolocoumarins and Furocoumarins

“…The plausible catalytic cycle for the formation of pyrrolocoumarin under the established copper‐catalyzed C−N coupling protocol is depicted in Figure 1 [16] . The 4‐(arylethynyl)‐3‐bromocoumarin initially involves in copper‐catalyzed hydroamination [16a,b] with in situ generated ammonia [15] to give the intermediate I – A and this upon oxidative addition [16c,d] with Cu(I) forms the intermediate I – B . It then undergoes cyclization and delivers the intermediate I – C .…”