Isoquinolinium Salts from<i>o</i>‐Halobenzaldehydes, Amines, and Alkynes Catalyzed by Nickel Complexes: Synthesis and Applications

“…However, only few synthetic methods are available in the literature, and they generally require prefunctionalized starting materials, multiple steps, and either stoichiometric or catalytic amounts of noble‐metal catalysts . Previously, we reported the synthesis of isoquinolinium salts from the annulation of either 2‐halobenzaldimines or 2‐iodoketimines with alkynes catalyzed by low‐valent nickel complexes. Later, we used rhodium and ruthenium complexes as the catalysts for preparing the nitrogen salts by C−H bond functionalization .…”

Section: Optimization Of Cobalt‐catalyzed Oxidative Annulation[a]mentioning

confidence: 99%

“…Later, we used rhodium and ruthenium complexes as the catalysts for preparing the nitrogen salts by C−H bond functionalization . Our continuing interest in metal‐catalyzed C−H bond activation and first‐row transition metal catalyzed reactions have stimulated us to investigate the nitrogen‐directed ortho C−H bond activation of arenes by cobalt complexes, followed by oxidative annulation with alkynes. Herein, we report the synthesis of various quaternary ammonium salts using pyridine, imine, and azo as the directing groups and [CoCp*(CO)I 2 ] as the catalyst.…”

Section: Optimization Of Cobalt‐catalyzed Oxidative Annulation[a]mentioning

confidence: 99%

Cobalt‐Catalyzed Oxidative Annulation of Nitrogen‐Containing Arenes with Alkynes: An Atom‐Economical Route to Heterocyclic Quaternary Ammonium Salts

2015

Self Cite

View full text Add to dashboard Cite

Four cobalt-catalyzed oxidative annulation reactions of nitrogen-containing arenes with alkynes proceeds by CÀH activation, thus leading to biologically useful quaternary ammonium salts,i ncluding pyridoisoquinolinium, cinnolinium, isoquinolinium, and quinolizinium salts,i nh igh yields. The results are comparable to those reactions catalyzedb y rhodium and ruthenium complexes.The transformation of the salts into various N-heterocycles has also been demonstrated.Transition metal catalyzed oxidative annulations of arenes through CÀHbond activation has drawn substantial attention because of their broad synthetic utility in the synthesis of natural products,d rugs,a nd materials. [1] Recently,m any nitrogen-containing,g roup-directed oxidative annulation reactions catalyzed by noble metals such as rhodium, ruthenium, palladium, and iridium, through CÀHa ctivation have been developed. [2] However,s imilar reactions using more abundant, less expensive,a nd less toxic first-row transition metals as the catalysts are still rare.Recently,f irst-row transition metal catalyzed C À Hb ond activation of arenes has become very attractive because these metals are less expensive,m ore abundant, and less toxic. [3] Thus,c obalt catalysts have been employed as alternative active C À Ha ctivation catalysts for rhodium and ruthenium complexes.I nt his context, the groups of Kanai, [4a-c] Ackermann, [4d,e] Glorius, [4f,g] Ellman, [4h-i] and Chang [4j,k] reported using high-valent cobalt catalysts for CÀHf unctionalization of arenes by various electrophiles.R ecently,M atsunaga, Kanai, and co-workers demonstrated the catalytic activity of [Co III Cp*] and [Rh III Cp*] in the synthesis of pyrroloindolones from N-carbamoyl indoles and alkynes. [4l] Very recently,t he groups of Kanai and Matsunaga, [4m] Ackermann, [4n] and Sundararaju [4o] individually reported isoquinoline synthesis by aredox-neutral strategy in the presence of [CoCp*(CO)I 2 ] as the catalyst. However,there is still no report on the cobaltcatalyzed CÀHo xidative annulation of arene with alkyne in the presence of an external oxidant.N-heterocyclic quaternary ammonium salts such as pyridoisoquinolinium, cinnolinium, pyridinium, and quinolizinium salts are found in the core structures of many bioactive compounds,p harmaceuticals,a nd organic materials. [5] How-

show abstract

“…It was however surprising to note that investigations on building the isoquinoline moiety via a nickel‐catalyzed Larock‐type annulation reaction is very rare. In 2005, Cheng and co‐workers reported a nickel‐catalyzed cyclization of 2‐iodobenzaldimines with alkynes to synthesize substituted isoquinolines (Scheme c) , . However, this method require high temperatures and the use of a stoichiometric metal reducing agent (Zn), thus limiting the further application of such a method.…”

Section: Introductionmentioning

confidence: 99%

Highly Regioselective Isoquinoline Synthesis via Nickel‐Catalyzed Iminoannulation of Alkynes at Room Temperature

et al. 2018

View full text Add to dashboard Cite

A simple and cost‐efficient nickel catalytic system for the annulation of 2‐haloaldimines with alkynes to synthesize 3,4‐disubstituted and 3‐substituted isoquinolines at room temperature has been developed. The air‐stable and inexpensive Ni(dppe)Cl2 was employed as a precatalyst, and Et3N was found to be an essential additive for obtaining high yields. By using this nickel catalytic system one‐pot three‐component direct synthesis of isoquinolines starting with simple 2‐halobenzaldehydes, tert‐butylamine, and alkynes were also achieved. These reactions occur in moderate to excellent yields with complete regioselectivity. Moreover, these reactions feature a broad substrate scope, easy scalability, operational simplicity, and excellent practicality.

show abstract

Isoquinolinium Salts fromo‐Halobenzaldehydes, Amines, and Alkynes Catalyzed by Nickel Complexes: Synthesis and Applications

Cited by 70 publications

References 55 publications

Transition Metal-Mediated Synthesis of Monocyclic Aromatic Heterocycles

Transition Metal-Mediated Synthesis of Monocyclic Aromatic Heterocycles

Cobalt‐Catalyzed Oxidative Annulation of Nitrogen‐Containing Arenes with Alkynes: An Atom‐Economical Route to Heterocyclic Quaternary Ammonium Salts

Highly Regioselective Isoquinoline Synthesis via Nickel‐Catalyzed Iminoannulation of Alkynes at Room Temperature

Contact Info

Product

Resources

About