An Efficient Protocol for Aza-Michael Addition Reactions Under Solvent-Free Condition Employing Sulfated Zirconia Catalyst

Reddy, Benjaram M.; Patil, Meghshyam K.; Reddy, Baddam T.

doi:10.1007/s10562-008-9646-7

Cited by 40 publications

(23 citation statements)

References 37 publications

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“…Contrastingly, catalysts are often used for aza-Michael additions when synthesizing drug molecules, allowing lower activation energies and thus increased rates of reaction. Example catalysts include boric acid (Chaudhuri et al, 2005), lipases (Dhake et al, 2010), sulfonated zirconia (Reddy et al, 2008), copper(II) acetylacetonate (Kantam et al, 2005), and indium trichloride (Yang et al, 2007) but more commonly observed is the use of lanthanide metal-centered catalysts (e.g., SmI 2 Reboule et al, 2005 and Yb(OTf) 2 Jenner, 1995). Such catalysts have been shown to be particularly efficient for promoting aza-Michael additions, their activity assumed to be a result of Lewis acid behavior drawing electron density away from the C=C and making the β-position more susceptible to attack from the nucleophilic amine.…”

Section: Resultsmentioning

confidence: 99%

Improving the Post-polymerization Modification of Bio-Based Itaconate Unsaturated Polyesters: Catalyzing Aza-Michael Additions With Reusable Iodine on Acidic Alumina

et al. 2019

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Bio-based platform molecules such as itaconic, fumaric, and muconic acid offer much promise in the formation of sustainable unsaturated polyester resins upon reaction with suitable diols and polyols. The C=C bonds present in these polyester chains allows for post-polymerization modification and such moieties are conventionally utilized in curing processes during the manufacture of coatings. The C=C modification sites can also act as points to add useful pendants which can alter the polymers final properties such as glass transition temperature, biodegradability, hardness, polarity, and strength. A commonly observed modification is the addition of secondary amines via an aza-Michael addition. Conventional procedures for the addition of amines onto itaconate polyesters require reaction times of several days as a result of undesired side reactions, in particular, the formation of the less reactive mesaconate regioisomer. The slow reversion of the mesaconate back to itaconate, followed by subsequent amine addition, is the primary reason for such extended reaction times. Herein we report our efforts toward finding a suitable catalyst for the aza-Michael addition of diethylamine onto a model substrate, dimethyl itaconate, with the aim of being able to add amine onto the itaconate units without excessive regioisomerization to the inactive mesaconate. A catalyst screen showed that iodine on acidic alumina results in an effective, heterogeneous, reusable catalyst for the investigated aza-Michael addition. Extending the study further, itaconate polyester was prepared by Candida Antartica Lipase B (CaL-B) via enzymatic polytranesterification and subsequently modified with diethylamine using the iodine on acidic alumina catalyst, dramatically reducing the required length of reaction (>70% addition after 4 h). The approach represents a multidisciplinary example whereby biocatalytic polymerization is combined with chemocatalytic modification of the resultant polyester for the formation of useful bio-based polyesters.

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Section: Resultsmentioning

confidence: 99%

Improving the Post-polymerization Modification of Bio-Based Itaconate Unsaturated Polyesters: Catalyzing Aza-Michael Additions With Reusable Iodine on Acidic Alumina

et al. 2019

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“…It has been realized in recent years that sulfuric acid adsorbed on silica gel could be used as a multipurpose acid catalyst [27][28][29][30][31]. In continuation of our work on the development of useful synthetic methodologies by employing solid acid catalysts [32][33][34][35], we observed that H 2 SO 4 /silica *Address correspondence to this author at the Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Uppal Road, Hyderabad -500 607, India; E-mails: bmreddy@iict.res.in, mreddyb@yahoo.com gel is an efficient catalyst for the synthesis of coumarins via Pechmann condensation. In this communication, we are disclosing our findings on H 2 SO 4 /silica gel catalyzed Pechmann condensation of a series of phenols and -keto esters to coumarins under solvent free conditions.…”

Section: Introductionmentioning

confidence: 82%

One-Pot Synthesis of Substituted Coumarins Catalyzed by Silica Gel Supported Sulfuric Acid Under Solvent-Free Conditions

M.¹,

Boningari²,

Patil³

2009

TOCATJ

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A remarkable acceleration in the synthesis of substituted coumarins via Pechmann reaction catalyzed by silica gel supported sulfuric acid (H 2 SO 4 /silica gel) at 120 °C in high yields under solvent-free reaction condition with short reaction times is described. This methodology offers momentous improvements over various options for the synthesis of coumarins with regard to yield of products, simplicity in operation and green aspects by avoiding toxic catalysts and solvents.

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“…Zeolites are natural (volcanic rock) or synthetic materials [1]. There are about fty natural zeolites and more than 150 synthetic zeolites [2]. The activity and the selectivity of the catalyst are in uenced by the characteristics of the catalyst when these characteristics depend on the method of preparation [3].…”

Section: Introductionmentioning

confidence: 99%

Catalyst H-ZSM 5 in Amines addition on Carbonyl Compounds α, β-unsaturated catalyzed by H-ZSM 5

M’hammed

Djafri

2021

Preprint

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Background Zeolites are crystallized aluminum silicates. Their structure consists of an arrangement of TO4 tetrahedral (T = Si, Al ...), creating a regular nonporous system made up of channels with a diameter of less than 1 nm and cages (the channel intersections). These materials were discovered by the mineralogist in 1756. These porous materials are used in the paper industry, in jewelry, and in other fields. Certain applications require pure materials with specific properties, hence the need to develop their synthesis. Zeolites are obtained hydrothermally at temperatures below 200°C. The dimensions of the pores are of the order of a nanometer, close to the dimensions of certain organic molecules which make these zeolitic materials find applications in various fields, separation by molecular sieving, purification by adsorption, cation exchange and catalysis. Result We are successful in the reaction of addition the series of amines to unsaturated alkenes, catalyzed by zeolite H-ZSM-5, the results show good products obtained with excellent yields, in short time, pure products can be obtained after filtering the catalyst and then removing the excess amines, the catalyst is recoverable, reactivated and reused several times for other addition reactions, the products were defined by 1 H NMR spectroscopy. Conclusion According to the results obtained. It can be said that the addition of various aliphatic or aromatic amines reacted successfully with alkenes, in the presence of the catalyst H-ZSM-5, to give the corresponding adducts with excellent yields in time and in perfect conditions, solvent-free and room temperature, so our H-ZSM-5 catalyst is effective, can meet our goal of adding amines to unsaturated carbonyl components.

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An Efficient Protocol for Aza-Michael Addition Reactions Under Solvent-Free Condition Employing Sulfated Zirconia Catalyst

Cited by 40 publications

References 37 publications

Improving the Post-polymerization Modification of Bio-Based Itaconate Unsaturated Polyesters: Catalyzing Aza-Michael Additions With Reusable Iodine on Acidic Alumina

Improving the Post-polymerization Modification of Bio-Based Itaconate Unsaturated Polyesters: Catalyzing Aza-Michael Additions With Reusable Iodine on Acidic Alumina

One-Pot Synthesis of Substituted Coumarins Catalyzed by Silica Gel Supported Sulfuric Acid Under Solvent-Free Conditions

Catalyst H-ZSM 5 in Amines addition on Carbonyl Compounds α, β-unsaturated catalyzed by H-ZSM 5

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