Browsing by Author "Annamalai, Pratheepkumar"

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Iptycenes with an acridinone motif developed through [4+2] cycloaddition of tethered naphthalene and iminoquinone via a radical reaction
(2017-06-11)
Raju, Selvam
;
Annamalai, Pratheepkumar
;
Chen, Pei-Ling
;
Liu, Yi-Hung
;
Chuang, Shih-Ching
A new class of iptycenes was developed by combining 2-(naphthalen-1-yl) anilines and p-benzoquinones through copper( II)-mediated radical cyclisation. This unusual cyclisation reaction resulted in the robust and efficient syntheses of iptycenes with an acridinone motif. These iptycenes can be further transformed into planar acridinone heterocyclics through the Diels-Alder reaction.
Palladium(II)-Catalyzed Mono- and Bis-alkenylation of N-Acetyl-2-aminobiaryls through Regioselective C-H Bond Activation
(2018-04-06)
Annamalai, Pratheepkumar
;
Hsu, Kou-Chi
;
Raju, Selvam
;
Hsiao, Huan-Chang
;
Chou, Chih-Wei
We developed palladium-catalyzed oxidative coupling of olefins with N-acyl 2-aminobiaryls through a sequence of ortho C-H bond activation/alkene insertion/reductive elimination. Furthermore, we controlled the selectivity of mono- and bis-alkenylation products with the solvent effect. The developed protocol was promising for a broad substrate scope ranging from activated olefins with a wide variety of functional groups to unactivated olefins.
Palladium-Catalyzed C-H Bond Activation by Using Iminoquinone as a Directing Group and an Internal Oxidant or a Co-oxidant: Production of Dihydrophenanthridines, Phenanthridines, and Carbazoles
(2017-08-04)
Raju, Selvam
;
Annamalai, Pratheepkumar
;
Chen, Pei-Ling
;
Liu, Yi-Hung
;
Chuang, Shih-Ching
A palladium-catalyzed C-H bond activation reaction, via a redox-neutral pathway, for the preparation of dihydrophenanthridine, phenanthridine, and carbazole derivatives from biaryl 2-iminoquinones is developed. The preinstalled iminoquinone was designed to act as a directing group for ortho C-H activation and an internal oxidant or a co-oxidant. This catalysis proceeded through the following sequence: C-H bond activation, coordination and insertion of activated olefins, beta-hydride elimination, H-shift, insertion, and protonation or beta-hydride elimination. using this method without the addition of external oxidants. In addition, carbazoles can be prepared efficiently by
Palladium-Catalyzed Regio- and Stereoselective Hydrosulfonation of Propiolate Esters
(2017-11-01)
Raju, Selvam
;
Annamalai, Pratheepkumar
;
Chan, Fu-Wei
;
Tseng, Po-Yen
;
Chen, Po-Yen
An efficient palladium-catalyzed addition reaction of alkyland arylsulfonic acids to propiolate esters to yield alkenyl sulfonates is demonstrated. The formation of alkenyl sulfonates is highly regio- and stereoselective with favorable yields of up to 95%, and two of the alkenyl sulfonates are utilized for a Sonogashira cross-coupling reaction to produce (Z)-1,3-enynoates.
Palladium-Catalyzed Selective Aryl Ring C-H Activation of N-Acyl-2-aminobiaryls: Efficient Access to Multiaryl-Substituted Naphthalenes
(2016-11-17)
Annamalai, Pratheepkumar
;
Chen, Wu-Yin
;
Raju, Selvam
;
Hsu, Kou-Chi
;
Upadhyay, Nitinkumar Satyadev
Palladium-catalyzed cycloaromatization of N-acyl-2-aminobiaryls, through a sequence of ortho C-H bond activation/alkyne insertion/meta C-H bond activation/alkyne insertion, was developed. An efficient synthesis of multiaryl-substituted naphthalenes, N-[2-(5,6,7,8-tetraarylnaphthalen-1-yl) aryl] acetamides, was demonstrated using molecular oxygen as the sole oxidant. Furthermore, through Buchwald\'s synthetic protocol, two compounds were converted into corresponding fluorescent carbazoles in 30-40% yield by intramolecular C-N bond formation.
Synthesis, Isolation, and Characterization of Mono- and Bis-norbornene-Annulated Biarylamines through Pseudo-Catellani Intermediates
(2019-02-15)
Annamalai, Pratheepkumar
;
Hsiao, Huan-Chang
;
Raju, Selvam
;
Fu, Yi-Hsuan
;
Chen, Pei-Ling
A palladium-catalyzed C-H functionalization of an external ring of N-acyl 2-aminobiaryl with bicyclo[2.2.1]-hept-2-ene (norbornene) via multiple C-H bond activations was developed. This study is the first report of the formation of bis-norbornene annulated biarylamines isomers (syn-3a'/anti-3a' = 36:64) from multiple C-H bond functionalizations. Additionally, nondirected C-H bond functionalization at the C-4' position with alkenes rendered complete C-H functionalization of five C-H bonds that formed a stable hexasubstituted benzene ring.