The reactivity of 3-methyl-4-nitro-5-styrylisoxazole with some bis-enolisable ketones

Adamo, Mauro F. A.; Chimichi, Stefano; Sio, F. De; Donati, Donato; Sarti‐Fantoni, P.

doi:10.1016/s0040-4039(02)00765-7

Cited by 40 publications

(24 citation statements)

References 15 publications

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“…The product was identified as 3-methyl-5-phenyl-4H-pyrrolo [2,3- lished by analytical and spectroscopic data and finally by comparing with authentic samples. 25) Contrary to our earlier method, 25) the reaction time was effectively reduced from hours (26)(27)(28) to minutes (15) in the present approach. The product yield was improved from 90 to 98%.…”

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confidence: 58%

“…This Michael reaction, when conducted on nitro styrylisoxazoles (3) in the presence of either triethyl amine or piperidine base in ethanol resulted in approximately 50% product formation and reaction required nearly 2-4 h refluxing, 27) and the reaction resulted in formation of by products. 28) Hence, ionic liquid mediated Michael addition has a clear advantage over the conventional base catalyzed reaction with regard to reduction in reaction time, increasing the yields, without forming undesired side-products. Moreover, the process is environmentally benign.…”

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confidence: 99%

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A Fast and Highly Efficient Protocol for Synthesis of Pyrrolo[2,3-d]isoxazoles and a New Series of Novel Benzyl Bis-pyrrolo[2,3-d]isoxazoles Using Task-Specific Ionic Liquids as Catalyst and Green Solvent

et al. 2010

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Regular ArticleSignificant progress in green chemistry is being made in several key research areas, such as catalysis, 1) the design of safer chemicals, environmentally benign solvents 2) and the development of renewable feed stocks. Chemists are trained to design products and processes with an increased awareness of environmental impact. Outreach activities within the green chemistry community highlight the potential for chemistry to solve many of the global environmental challenges. In the recent years, ionic liquids have emerged as green solvents with desirable properties such as good solvating ability, wide liquidous range, tunable polarity, high thermal stability, negligible vapour pressure and ease of recyclability. These are referred to as designer solvents since they exhibit properties like hydrophilicity, hydrophobicity, Lewis acidity, viscosity and density. These can be altered by the fine tuning of parameters such as the choice of organic cation and the length of alkyl chain attached to an organic cation. These structural variations offer flexibility to the chemists to devise the most idealized solvent catering to the needs of any particular process. Due to the stabilization of charged intermediates by ionic liquids, they can promote unprecedented selectivities and enhanced reaction rates. Consequently, ionic liquids are being used as recyclable solvents for the immobilization of transition metal-based catalysts, Lewis acids and enzymes. During the past few years, a variety of room temperature ionic liquids have been demonstrated as efficient and practical alternatives to organic solvents for many important organic transformations. [3][4][5][6][7][8][9] Particularly, the use of [bmIm]OH as a novel and a recyclable reaction medium, as well as an efficient catalyst for Knoevenagel and Michael reactions has been reported in literature. [10][11][12] Similarly, 1-methyl imidazolium tetrafluoroborates has been exploited as an efficient Bronsted acid promoter ionic liquid in various organic transformations. [13][14][15] As a part of our study on environmentally friendly organic synthesis with isoxazoles, [16][17][18][19] avoiding organic solvent and toxic catalyst in reactions, we demonstrated the use of room temperature ionic liquids as efficient catalysts as well as reaction media for Knoevenagel and Michael reactions and also for conducting reductive cyclization.Looking for a valuable procedure for the conversion of nitro styrylisoxazoles (3) to pyrrolo[2,3-d]isoxazoles (4), several approaches have been investigated. One method for pyrrole ring formation is by de-oxygenative cyclization of nitro styryl compounds using triethyl phosphite (TEP). [20][21][22] As the reaction requires heating of the nitro styrylisoxazole (3) in TEP at high temperature under N 2 atmosphere, the reaction results in cleavage of the isoxazole ring, which is unstable at higher temperature. 23) To overcome this problem, another method developed by Angelo Carotti 24) is employed, which involves the reductive cyclization of a nitro s...

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confidence: 58%

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confidence: 99%

A Fast and Highly Efficient Protocol for Synthesis of Pyrrolo[2,3-d]isoxazoles and a New Series of Novel Benzyl Bis-pyrrolo[2,3-d]isoxazoles Using Task-Specific Ionic Liquids as Catalyst and Green Solvent

et al. 2010

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“…3-Methyl-4-Nitro-5-styrylisoxazoles 1 [1][2][3][4][5][6][7][8][9] and 2 [3] (Scheme 1) represent two types of polyfunctional scaffold which hold excellent potential for the generation of diversity ( Figure 1) [1][2][3][4][5][6][7][8][9]. Compounds 1 and 2 can be readily prepared from commercially available 3,5-dimethyl-4-nitroisoxazole 3 and aromatic aldehydes 4 ( Figure 1) [10].…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, compounds 1 have two electrophilic centers that can be selectively reacted. Enolates, which are stabilized soft nucleophiles, react at the soft electrophilic center E2, whereas hard nucleophiles such as hydroxide react exclusively at the hard electrophilic center E1 ( Figure 1) [1][2][3][4][5][6][7][8][9][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Cyclopropanation of 5-(1-Bromo-2-phenyl-vinyl)-3-methyl-4-nitro-isoxazoles under Phase Transfer Catalysis (PTC) Conditions

et al. 2015

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“…However, the base catalysed method sometimes suffers from disadvantages of incompatibility with base-sensitive functionality and the occurrence of other side reactions, such as autocondensations and retro-Michael type decompositions. When we carried out the Michael addition on isoxazole derivatives in presence of Et 3 N 11 , the reaction required long heating periods and the product yields were only moderate and unwanted side products were formed 12 .…”

Section: Introductionmentioning

confidence: 99%

p-TsOH catalysed KSF solid supported Michael addition with substituted isoxazoles and their reductive cyclisation to isoxazolo[4,5-b]azepines

Rajanarendar¹,

Ramesh²,

Rao³

et al. 2007

Arkivoc

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The reactivity of 3-methyl-4-nitro-5-styrylisoxazole with some bis-enolisable ketones

Cited by 40 publications

References 15 publications

A Fast and Highly Efficient Protocol for Synthesis of Pyrrolo[2,3-d]isoxazoles and a New Series of Novel Benzyl Bis-pyrrolo[2,3-d]isoxazoles Using Task-Specific Ionic Liquids as Catalyst and Green Solvent

A Fast and Highly Efficient Protocol for Synthesis of Pyrrolo[2,3-d]isoxazoles and a New Series of Novel Benzyl Bis-pyrrolo[2,3-d]isoxazoles Using Task-Specific Ionic Liquids as Catalyst and Green Solvent

Cyclopropanation of 5-(1-Bromo-2-phenyl-vinyl)-3-methyl-4-nitro-isoxazoles under Phase Transfer Catalysis (PTC) Conditions

p-TsOH catalysed KSF solid supported Michael addition with substituted isoxazoles and their reductive cyclisation to isoxazolo[4,5-b]azepines

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