Browsing by Author "Barve, Indrajeet J."

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Base Controlled Three-Component Regioselective Synthesis of 2-Imino Thiazolines and 2-Thioxoimidazolin-4-ones
(2019-04-01)
Barve, Indrajeet J.
;
Chang, Wong-Jin
;
Lin, Yen-Tzu
;
Thikekar, Tushar Ulhas
;
Sun, Chung-Ming
Base-controlled regioselective synthesis of 2-imino thiazolines and 2-thioxoimidazolin-4-ones was achieved to use a one-pot reaction between chiral amino esters, isothiocyanates, and alpha-bromoketones/alkyl halides. This three-component coupling reaction in acetonitrile provides 2-imino thiazolines, whereas the formation of 2-thioxoimidazolin-4-ones was observed under basic conditions at ambient temperature. The corresponding products were obtained in good to excellent yield with broad substrate scope. Isolation of thiourea and thiohydantoin intermediates disclosed the course of the reaction mechanism.
Catalyst-Controlled Regioselective Synthesis of Benzotriazlolodiazepin-7-ones and Benzotriazolodiazocin-8-ones
(2020-01-17)
Chen, Kai-Chi
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Barve, Indrajeet J.
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Sun, Chung-Ming
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應用化學系
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Department of Applied Chemistry
A catalyst-controlled highly chemoselective and regioselective intramolecular cycloamidation of triazol-1-ylbenzamides toward the synthesis of scarcely known heterocycles is reported. In the presence of a palladium catalyst, this cycloisomerization reaction afforded substituted benzotriazlolodiazepin-7-ones via intramolecular insertion of a palladium into C-C triple bond in a 7-exo-dig way. Alternatively, the use of a silver catalyst in the reaction produced substituted benzotriazolodiazocin-8-ones in a highly regioselective manner through 8-endo-dig intramolecular ring closure.
Design and Synthesis of New Biprivileged Molecular Scaffolds: Indolo-Fused Benzodiazepinyl/quinoxalinyl benzimidazoles
(2012-06-01)
Barve, Indrajeet J.
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Chen, Chan-Yu
;
Salunke, Deepak B.
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Chung, Wen-Sheng
;
Sun, Chung-Ming
The present article describes the design and synthesis of new biprivileged molecular scaffolds with diverse structural features. Commercially available, simple heterocyclic building blocks such as 4-fluoro-3-nitrobenzoic acid, 2-chloro-3-nitrobenzoic acid, and indoline were utilized for the synthesis of the novel heterocycles. PictetSpengler-type condensation was used as a key step to construct tetracyclic indolo-benzodiazepines and indolo-quinoxalines linked with substituted benzimidazoles. Analysis of single crystals of representative compounds showed that these molecular skeletons have the potential to present various substituents with distinct three-dimensional orientations.
Design, synthesis and diversification of natural product-inspired hydantoin-fused tetrahydroazepino indoles
(2015-01-01)
Barve, Indrajeet J.
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Dalvi, Prashant B.
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Thikekar, Tushar Ulhas
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Chanda, Kaushik
;
Liu, Yu-Li
A facile and efficient synthesis of novel oxo, thio and seleno hydantoin fused tetrahydroazepino [4,5-b] indoles was reported. A naturally occurring iboga class alkaloid inspired seven-membered azepino[4,5-b] indole ring was synthesized as a new scaffold through Pictet-Spengler reaction followed by skeletal rearrangement of the aziridine ring. To improve the efficiency of the synthetic route, the double bond of the rearranged olefinic product 5 was reduced and a privileged hydantoin moiety was constructed on the core system through urea formation using a variety of isocyanates, isothiocyanates and isoselenocyanates followed by intramolecular cyclization to incorporate elements of diversity. The regeneration of the double bond of intermediate 9 afforded hydantoin-fused tetrahydroazepino [4,5-b] indoles.
Enantioselective synthesis of (-)-(R) Silodosin by ultrasound-assisted diastereomeric crystallization
(2013-04-01)
Barve, Indrajeet J.
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Chen, Li-Hsun
;
Wei, Patrick C. P.
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Hung, Jui-Te
;
Sun, Chung-Ming
Enantioselective synthesis of clinically approved drug Silodosin for the treatment of benign prostatic hyperplasia from the commercially available compounds 1-acetyl-5-(2-aminopropyl) indoline-7-carbonitrile A and 2-(2-(2,2,2-trifluoroethoxy)phenoxy)ethyl methanesulfonate C is explored. Key step in the synthesis is chiral resolution of intermediate I, which was achieved by a simple diastereomeric crystallization using (S)-(+)-mandelic acid assisted by ultrasonication. The present synthetic strategy has lesser number of steps and is vastly improved the overall yield in this short route towards target compound Silodosin. (C) 2013 Elsevier Ltd. All rights reserved.
Enantioselective Synthesis of Hydantoin and Diketopiperazine-Fused Tetrahydroisoquinolines via Pictet-Spengler Reaction
(2019-04-01)
Liu, Shih-I
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Haung, Jia-Yun
;
Barve, Indrajeet J.
;
Huang, Sheng-Cih
;
Sun, Chung-Ming
An enantioselective synthesis of iso-, isothio-, and isoselenohydantoin and diketopiperazine-fused tetrahydroisoquinolines from L-Dopa was reported. The route consists of an Pictet-Spengler reaction of (S)-2-amino-3-(3,4-dimethoxyphenyl)propanoates with various aldehydes to afford diastereomeric tetrahydroisoquinolines. Next step, the tetrahydroisoquinolines were further reacted with iso-, isothio-, or isoselenocyanates to construct hydantoin. Similarly, the diketopiperazine moiety was constructed by subjecting tetrahydroisoquinolines to a condensation reaction with chloroacetyl chloride followed by nucleophilic addition with various primary amines.
Enantiospecific Synthesis of Imidazoquinazolin-2-ones via Base-Catalyzed Tandem Cyclization
(2017-09-29)
Kumar, Sunil
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Ho, Pei-Heng
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Barve, Indrajeet J.
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Sun, Chung-Ming
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應用化學系
A facile protocol for the enantiospecific synthesis of novel (S)-3-substituted imidazo[2,l-b]quinazoline-2-ones via tandem reaction of substituted (S)-3-amino-4-aminomethylbenzoates and cyanogen bromide under basic conditions is explored. This tandem process involves addition reaction of substituted (S)-3-amino-4-aminomethylbenzoates to CNBr to yield 2-imino tetrahydroquinazoline carboxylate intermediates followed by insitu intramolecular aminolysis to afford the triheterocyclic imidazo[2,l-b]quinazoline-2-ones in good yields and high enantiomeric purity.
Microwave-Assisted Synthesis of Benzimidazole-Linked Indoline and Indole Hybrids from C-2 Linked (o-Aminobenzyl)benzimidazoles
(2018-02-01)
Lee, Yun-Ta
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Chiu, Feng-Yu
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Barve, Indrajeet J.
;
Sun, Chung-Ming
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應用化學系
An efficient and novel synthesis of benzimidazole-linked indoline hybrids via an unconventional Pictet-Spengler-type condensation of C-2 linked (o-aminobenzyl) benzimidazoles with aldehydes and ketones under microwave irradiation has been explored. The key condensation step consists of acid-catalyzed imine generation followed by intramolecular C-C bond formation through unique reactivity of the benzimidazole moiety. The scope of this method is further extended to synthesize tetracyclic pyrroloindole benzimidazole-carboxylates through 2-carboxaldehydes.
One-pot synthesis of 4-arylidene imidazolin-5-ones by reaction of amino acid esters with isocyanates and alpha-bromoketones
(2019-03-21)
Haung, Jia-Yun
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Barve, Indrajeet J.
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Sun, Chung-Ming
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應用化學系
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Department of Applied Chemistry
A simple and new multicomponent reaction for the one-pot synthesis of substituted 4-arylidene imidazolin- 5-ones from L-amino acid methyl esters, iso-, isothio-or isoselenocyanates, and alpha-bromoketones is demonstrated. Isolation of thiohydantoin and 5-benzylidene 2-thioxoimidazolidin-4-one intermediates revealed a possible reaction mechanism. The strategy was further extended to the synthesis of 2-iminothiazolines and 2-thioxoimidazolin-4-ones.
One-Pot Synthesis of Unsymmetrical Bis-Heterocycles: Benzimidazole-, Benzoxazole-, and Benzothiazole-Linked Thiazolidines
(2020-01-01)
Lu, Hsueh-Yuan
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Barve, Indrajeet J.
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Selvaraju, Manikandan
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Sun, Chung-Ming
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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.
One-Pot Three-Component Synthesis of 2-Imino-1,3-Thiazolines on Soluble Ionic Liquid Support
(2016-10)
Chen, Chan-Yu
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Barve, Indrajeet J.
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Sun, Chung-Ming
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應用化學系
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Department of Applied Chemistry
An efficient one-pot, three-component synthesis of 2-imino-1,3-thiazolidines and 2-imino-1,3-thiazolines using ionic liquid-tethered 2-aminobenzimidazoles was reported. The protocol includes reaction of ionic liquid attached 2-aminobenzimidazoles with isothiocyanates to afford isothioureas, followed by its base induced inter and intramolecular nucleophilic displacement reactions with 1,2-dichloroethane (EDC) which results in thiazolidine ring formation. In the next to the last step, the ionic liquid support was removed by methanolysis to deliver 2-imino-1,3-thiazolidines, which were sequentially oxidized with manganese(III) triacetate to yield 2-imino-1,3-thiazolines. The salient feature of this method is the use of 1,2-dichloroethane as a synthetic equivalent for alpha-haloketone to avoid the use of toxic halogenating reagents.
Regioselective Piperidine-Catalyzed Tandem Imination-Isocyanate Annulation to Fused Tricyclic Triazines
(2014-05-01)
Barve, Indrajeet J.
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Chen, Chih-Hau
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Kao, Chih-Hsien
;
Sun, Chung-Ming
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應用化學系
A novel tandem imination-isocyanate-mediated annulation was explored. Ionic liquid-immobilized 2-aminobenzimidazoles react sequentially with aldehydes and isocyanates to give highly functionalized benzimidazole-embedded triazines. The second-stage transformation revealed that the formation of triazinone functionality is entirely regioselective to allow rapid assembly of biologically interesting tricyclic skeletons. In conjunction with the application of microwave irradiation and IL support, this method provides an efficient route to access substituted benzoimidazotriazines.
Regioselective synthesis of imidazo[1,5-a]quinoxalines and methyl N-phenylbenzimidats on an ionic liquid support
(2016-01-01)
Chen, Li-Hsun
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Kao, Chih-Hsien
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Dhole, Sandip
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Barve, Indrajeet J.
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Shen, Li-Ching
An ionic liquid (IL) supported, regioselective synthesis of imidazo[1,5-a]quinoxalines and methyl N-phenylbenzimidats under microwave conditions was reported. The IL-immobilized aromatic amines were reacted with various ketones and aliphatic aldehydes using an unconventional Pictet-Spengler reaction to generate polycyclic imidazo[1,5-a]quinoxalines. Alternatively, aromatic aldehydes afforded auto-oxidized imidazo[1,5-a]quinoxalines first which further converted to novel methyl N-phenylbenzimidats unexpectedly during the cleavage of the IL-support. In the reported strategy, rapidness is achieved through microwave conditions while the IL-support assists purification by simple precipitation.
Regioselective synthesis of imidazo[1,5-a]quinoxalines and methyl N-phenylbenzimidats on an ionic liquid support
(2016-01-01)
Chen, Li-Hsun
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Kao, Chih-Hsien
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Dhole, Sandip
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Barve, Indrajeet J.
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Shen, Li-Ching
An ionic liquid (IL) supported, regioselective synthesis of imidazo[1,5-a]quinoxalines and methyl N-phenylbenzimidats under microwave conditions was reported. The IL-immobilized aromatic amines were reacted with various ketones and aliphatic aldehydes using an unconventional Pictet-Spengler reaction to generate polycyclic imidazo[1,5-a]quinoxalines. Alternatively, aromatic aldehydes afforded auto-oxidized imidazo[1,5-a]quinoxalines first which further converted to novel methyl N-phenylbenzimidats unexpectedly during the cleavage of the IL-support. In the reported strategy, rapidness is achieved through microwave conditions while the IL-support assists purification by simple precipitation.
Silver(I)-Catalyzed Regioselective Synthesis of Triazole Fused-1,5-Benzoxazocinones
(2017-05-05)
Barve, Indrajeet J.
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Thikekar, Tushar Ulhas
;
Sun, Chung-Ming
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應用化學系
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Department of Applied Chemistry
An efficient and regioselective synthesis of novel 1,2,3-triazole-fused-1,5-benzoxazocinones through intramolecular cyclization of substituted ethynyl triazoyl benzoic acids was explored. A crucial precursor 5-iodo-1,2,3-triazole benzoate was obtained from substituted 2-azido benzoic acid esters in a single step through a Copper-Catalyzed Azide-Alkyne Cycloaddition (CuAAC) reaction using a CuI/NBS catalytic system. A carbon carbon triple bond was installed through a Sonogashira coupling reaction by various terminal alkynes. Finally, the 1,4,5-substituted ethynyl triazoyl benzoic acids were cyclized by a AgOTf-mediated intramolecular cyclization to afford 8-endo-dig 1,2,3-triazole-fused-1,5-benzoxazocinones exclusively.
Synthesis of Aminofuran-Linked Benzimidazoles and Cyanopyrrole-Fused Benzimidazoles by Condition-Based Skeletal Divergence
(2017-07-01)
Hsu, Wei-Shun
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Tsai, Min-Huan
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Barve, Indrajeet J.
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Yellol, Gorakh S.
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Sun, Chung-Ming
A condition-based skeletal divergent synthesis was explored to achieve skeletal diversity in two component condensation reaction. Cyanomethyl benzimidazole was reacted with alpha-bromoketone under thermal conditions to furnish 2-aminofuranyl-benzimidazoles, while the same reaction afforded 3-cyano-benzopyrrolo-imidazoles under microwave irradiation. Two nonequivalent nucleophilic centers on benzimidazole moiety were manipulated elegantly by different reaction conditions to achieve the skeletal diversity.