Browsing by Author "Selvaraju, Manikandan"

Now showing 1 - 16 of 16

Cascade Synthesis of Benzimidazole-Linked Pyrroles via Copper Catalyzed Oxidative Cyclization and Ketonization
(2017-06-16)
Ye, Tzuen-Yang
;
Selvaraju, Manikandan
;
Sun, Chung-Ming
;
應用化學系
;
Department of Applied Chemistry
A three-component cascade reaction of 2-aminobenzimidazole, aldehyde, and terminal alkyne has been explored for an efficient synthesis, of benzimidazole-linked tetrasubstituted pyrroles. The reaction sequence involves the formation Of propargylamine, insertion of 4 terminal alkyne, and a ring opening reaction, followed by, an intramolecular carboylative cyclization under aerobic conditions. It represents a novel, strategy to the construction of C=N, C=C, C=0 bonds and a new five-membered 2-ketopyrrole ring. In this process, the reaction conditions are crucial and an attempt to elucidate the novel reaction patway is well, supported by X=ray crystallography.
Copper catalyzed aerobic oxidative cyclization and ketonization: one pot synthesis of benzoimidazo[1,2-a]imidazolones
(2016)
Selvaraju, Manikandan
;
Ye, Tzuen-Yang
;
Li, Chia-Hsin
;
Ho, Pei-Heng
;
Sun, Chung-Ming
A highly efficient synthesis of benzoimidazo[1,2-a]imidazolone through a novel oxidative 5-exo-dig cyclization-ketonization cascade of 2-aminobenzimidazole, aldehyde and terminal alkyne has been explored under aerobic conditions. The reaction proceeds through copper-catalyzed addition of terminal alkynes to imines derived from 2-aminobenzimidazole with aldehyde followed by intramolecular cyclization. The atmospheric molecular oxygen acts as an oxygen source for the newly formed carbonyl group in the final product.
Ionic liquid supported synthesis of tricyclic pyrimido [1,2-a]benzimidazoles by a telescoped Michael/hetero annulation strategy
(2013)
Selvaraju, Manikandan
;
Shiu, Wei-Shuen
;
Kulkarni, Manohar V.
;
Sun, Chung-Ming
;
應用化學系
A telescoped sequence involves the reaction of cationic imidazolium attached 2-aminobenzimidazoles with in situ generated 1,1-dicyano-2-aryl ethylenes was explored for the regioselective synthesis of pyrimido[1,2-a]benzimidazoles. The perceived regioselectivity was presumed in terms of preferential Michael addition of 2-aminobenzimidazole followed by intramolecular annulation to the exclusive formation of 4-iminopyrimidines on an ionic liquid support. A plausible mechanistic pathway for their selective formation is discussed and fully supported by X-ray analysis. The present strategy reveals both the amine function and the ring nitrogen in substituted 2-aminobenzimidazoles are active sites for nucleophilic attack on alpha,beta-unsaturated nitriles.
Microwave Controlled Reductive Cyclization: A Selective Synthesis of Novel Benzimidazole-alkyloxypyrrolo[1,2-a]quinoxalinones
(2015-05-01)
Dhole, Sandip
;
Selvaraju, Manikandan
;
Maiti, Barnali
;
Chanda, Kaushik
;
Sun, Chung-Ming
An efficient cascade synthesis of novel benzimidazole linked alkyloxypyrrolo[1,2-a]quinoxalinones was explored on soluble polymer support under micro-Wave irradiation. Two exclusive protocols have been developed for the partial and reductive cyclization by Controlling the microwave energy, Commencing from the smile substrate, ortho nitro, pyrrol: carboxylates, N-hydroxy pyrroloquinoxalinones were obtained by,, partial reductive cyclization (60 degrees C, 7 min), and the synthesis of pyrroloquinoxalinones was accomplished by full reductive, cyclization (85 degrees C, 12 min). This method represents the first synthesis N-hydroxy pyrroloquinoxalinones using Pd/C and ammonium formate as reducing agents: Further employing a variety Of alkyl bromides, the obtained pyrroloquinoxalinones were transformed to their corresponding O-, and N-alkylated analogues to deliver the diversified, novel molecular entities.
Multicomponent Solvent-Free Synthesis Of Benzimidazolyl Imidazo[1,2-a]-pyridine Under Microwave Irradiation
(2013-06-01)
Maiti, Barnali
;
Chanda, Kaushik
;
Selvaraju, Manikandan
;
Tseng, Chih-Chung
;
Sun, Chung-Ming
A novel one-pot, three-component reaction employing variously substituted benzimidazole-linked amino pyridines, aldehydes, and isonitriles catalyzed by scandium(III) triflate under solvent-free conditions were accomplished. This new synthetic methodology facilitates the rapid generation of intricate molecular frameworks in three-dimensional fashion leading to benzinaidazole-imidazo [1,2-a] pyridines. This approach is envisioned as an environmentally benign process and a simple operation to the biological interesting compounds. The present synthetic sequence permits the introduction of three points of structural diversity to expand chemical space with high purity and excellent yields.
Multistep divergent synthesis of benzimidazole linked benzoxazole/benzothiazole via copper catalyzed domino annulation
(2013)
Liao, Jen-Yu
;
Selvaraju, Manikandan
;
Chen, Chih-Hau
;
Sun, Chung-Ming
;
應用化學系
An efficient, facile synthesis of structurally diverse benzimidazole integrated benzoxazole and benzothiazoles has been developed. In a multi-step synthetic sequence, 4-fluoro-3-nitrobenzoic acid was converted into benzimidazole bis-heterocycles, via the intermediacy of benzimidazole linked ortho-chloro amines. The amphiphilic reactivity of this intermediate was designed to achieve the title compounds by the reaction of various acid chlorides and isothiocyanates in a single step through the in situ formation of ortho-chloro anilides and thioureas under microwave irradiation. A versatile one pot domino annulation reaction was developed to involve the reaction of benzimidazole linked ortho-chloro amines with acid chlorides and isothiocyanates. The initial acylation and urea formation followed by copper catalyzed intramolecular C-O and C-S cross coupling reactions furnished the angularly oriented bis-heterocycles which bear a close resemblance to the streptomyces antibiotic UK-1.
One-pot synthesis of benzazoles and quinazolinones via iron pentacarbonyl mediated carbonylation of aryl iodides under microwave irradiation
(2017)
Lin, Wun-Huei
;
Wu, Wen-Chun
;
Selvaraju, Manikandan
;
Sun, Chung-Ming
;
應用化學系
A direct and unconventional method for the synthesis of benzazoles and quinazolinones is discovered by using iron pentacarbonyl as a reducing agent and a carbon monoxide source under microwave irradiation. The reaction of substituted aryl iodides with o-amino/mercapto/hydroxyl nitrobenzenes and o-nitrobenzamides successfully delivered a wide variety of benzazoles and quinazolinones, respectively.
One-pot synthesis of benzazoles and quinazolinones via iron pentacarbonyl mediated carbonylation of aryl iodides under microwave irradiation
(2017)
Lin, Wun-Huei
;
Wu, Wen-Chun
;
Selvaraju, Manikandan
;
Sun, Chung-Ming
;
應用化學系
A direct and unconventional method for the synthesis of benzazoles and quinazolinones is discovered by using iron pentacarbonyl as a reducing agent and a carbon monoxide source under microwave irradiation. The reaction of substituted aryl iodides with o-amino/mercapto/hydroxyl nitrobenzenes and o-nitrobenzamides successfully delivered a wide variety of benzazoles and quinazolinones, respectively.
One-Pot Synthesis of Triazoloquinazolinones via Copper-Catalyzed Tandem Click and Intramolecular C-H Amidation
(2014-04-14)
Selvaraju, Manikandan
;
Sun, Chung-Ming
;
應用化學系
;
Department of Applied Chemistry
A novel and highly efficient copper-catalyzed tandem synthesis of triazoloquinazolinones is explored. The synthetic strategy involves a sequential one-pot click reaction followed by aerobic intramolecular CH amidation. Two distinct and important transformations were carried out in one-pot by employing a single cost-effective copper catalyst. The milder, rapid and ligand-free reaction conditions as well as a broader substrate scope are the salient features of this novel protocol.
One-Pot Synthesis of Unsymmetrical Bis-Heterocycles: Benzimidazole-, Benzoxazole-, and Benzothiazole-Linked Thiazolidines
(2020-01-01)
Lu, Hsueh-Yuan
;
Barve, Indrajeet J.
;
Selvaraju, Manikandan
;
Sun, Chung-Ming
;
應用化學系
A one-pot, three-component synthesis of benzimidazole-linked thiazolidines from 2-cyanomethyl benzimidazole, iso-, isothio-, or isoselenocyanates and 1,2-dichloroethane is reported. Isolation of the key intermediate formed during the course of the reaction validates its mechanistic pathway. Under the same reaction conditions, benzimidazole-linked/fused thiazinanes were obtained when 1,3-dichloropropane or diiodomethane was used.
Parallel synthesis and biological evolution of quinic acid derivatives as immuno-suppressing agents against T-cell receptors
(2015-01-01)
Huang, Chih-Yu
;
Chen, Li-Hsun
;
Huang, Hsuan-Yu
;
Kao, Feng-Sheng
;
Lee, Yun-Ta
A simple protocol for the synthesis of quinic acid derivatives was established and their biological evolution against T-cells is studied. Results showed that one of the derivatives, Cyn-1324, has low toxicity on T-cells and a high effect on reducing Signal 2 of T-cell immune responses. In vitro binding measurements of atomic force spectroscopy further indicated that the blocking effect of Cyn-1324 between CD28 and CD80 was about 31 + 4%. In vivo animal tests also confirmed that Cyn-1324 can reduce the allergic responses from ovalbumin-induced mice with little toxicity. Based on these observations, Cyn-1324 can be a mild immuno-suppressive candidate for future drug development.
Regioselective Synthesis of Pyranone-Fused Indazoles via Reductive Cyclization and Alkyne Insertion
(2018-03-01)
Wu, Tz-Yi
;
Dhole, Sandip
;
Selvaraju, Manikandan
;
Sun, Chung-Ming
;
應用化學系
A novel and efficient method for the one-pot synthesis of 2H-indazole from readily available building blocks is reported. The reaction of 2-nitrobenzylamines with zinc and ammonium formate underwent partial reduction to nitroso-benzylamine followed by an intramolecular cyclization to afford 2H-indazole via N-N bond formation. The carboxylic acid moiety of indazole was proceeded to regioselective alkyne insertion under ruthenium catalysis to form pyranone-fused indazoles. The regioselectivity is influenced by the weak coordination of indazole ring nitrogen to the metal center.
Ruthenium(II)-catalyzed C-H alkenylation/annulation cascade for the rapid synthesis of benzoimidazoisoindoles
(2017-07-01)
Selvaraju, Manikandan
;
Wang, Ying-Lien
;
Sun, Chung-Ming
;
應用化學系
;
Department of Applied Chemistry
An efficient one pot synthesis of benzimidazole-fused isoindoles from 2-arylbenzimidazole and readily available conjugated alkenes has been explored. The developed domino strategy involved the ruthenium-catalyzed formation of two distinct C-C and C-N bonds and one new five-membered ring to afford a polycyclic molecule. The rapid and base-free reaction conditions and the broader substrate scope are salient features of this novel protocol. The ruthenium-catalyzed tandem reaction provides a direct tool for the easy and rapid access to a new benzoimidazoisoindole scaffold.
Skeletally Diverse Synthesis of Indole-Fused Diazocine and Diazepine Frameworks by One-Pot, Two-Component Cascade Reaction
(2016-01-15)
Thikekar, Tushar Ulhas
;
Selvaraju, Manikandan
;
Sun, Chung-Ming
;
應用化學系
;
Department of Applied Chemistry
An expeditious and novel strategy has been explored for the synthesis of structurally diverse indole-fused diazocine and diazepine derivatives. A substrate-based diversification approach of methyl-3-aminoindole/indoline benzoates coupled with the Pictet-Spengler reaction and three different reaction cascades furnished indolodiazepine and indoloquinoxalines. The formation of indolodiazocines proceeds through an initial condensation followed by intramolecular alkylation.
Three Component Divergent Reactions: Base-Controlled Amphiphilic Synthesis of Benzimidazole-Linked Thiazetidines and Fused Thiadiazines
(2016-10-07)
Selvaraju, Manikandan
;
Dhole, Sandip
;
Sun, Chung-Ming
;
應用化學系
;
Department of Applied Chemistry
A divergent reaction of 2-aminobenzimidazole with isothiocyanates and dihalomethanes has been developed for the selective synthesis of benzoimidazothiazetidine and benzoimidazothiadiazine. A single-pot reaction of 2-aminobenzimidazole in the presence of sodium hydride delivers benzoimidazothiazetidine, whereas triethylamine promotes the formation of benzoimidazothiadiazine via a sequential stepwise, fashion. The reaction sequence involves the initial formation of thiourea followed by regioselective nucleophilic addition and intramolecular ring-closing with dihalo electrophiles. The observed regioselectivity,of this reaction is governed by the nature of bases and the reaction sequence.
Unprecedented One-Pot Chemocontrolled Entry to Thioxoimidazolidinones and Aminoimidazolones: Synthesis of Kinase Inhibitor Leucettamine B
(2015-03-01)
Selvaraju, Manikandan
;
Sun, Chung-Ming
;
應用化學系
;
Department of Applied Chemistry
A novel and highly chemoselective protocol for the construction of thioxoimidazolidinone and aminoimidazolone frameworks was explored, and the influence of the reaction conditions on product formation was studied to establish two distinct approaches for their selective formation. In this one-pot reaction, ambient temperature generally resulted in the formation of thioxoimidazolidinones, whereas microwave irradiation provided aminoimidazolones exclusively. An attempt to elucidate the observed chemoselectivity is described, and the products were confirmed by X-ray studies. One-pot synthesis toward Leucettamine B, a marine alkaloid, was achieved on the basis of this protocol.