N-Bromosuccinimide (NBS) — Selective and effective catalyst for trimethylsilylation of alcohols and phenols using hexamethyldisilazane and their regeneration under mild and neutral reaction conditions

2007 ◽  
Vol 85 (5) ◽  
pp. 336-340 ◽  
Author(s):  
Ardeshir Khazaei ◽  
Amin Rostami ◽  
Ayeh Raiatzadeh ◽  
Marjan Mahboubifar
Keyword(s):  
Room Temperature ◽  
Trimethylsilyl Ether ◽  
Catalytic Amount ◽  
Solvent Free ◽  
Reaction Conditions ◽  
Effective Catalyst ◽  
Neutral Reaction ◽  
Trimethylsilyl Ethers ◽  
Solvent Free Conditions

Structurally diverse alcohols and phenols were trimethylsilylated in a clean and efficient reaction with hexamethyldisilazane (HMDS) based on the use of a catalytic amount of N-bromosuccinimide under both dichloromethane and solvent-free conditions at room temperature. Deprotection of trimethylsilyl ethers was also be achieved efficiently in the presence of a catalytic amount of NBS in methanol at ambient temperature.Key words: N-bromosuccinimide, solvent-free, alcohols, phenols, hexamethyldisilazane, trimethylsilyl ether, catalyst, detrimethylsilylation.

Rapid synthesis of homoallylic alcohol from aldehyde with allyltributylstannane under solvent-free conditions

2012 ◽  
Vol 90 (2) ◽  
pp. 167-172 ◽  
Author(s):  
Pranjal P. Bora ◽  
H. Atoholi Sema ◽  
Barisha Wahlang ◽  
Ghanashyam Bez
Keyword(s):  
Reaction Time ◽  
Phosphotungstic Acid ◽  
Catalytic Amount ◽  
Solvent Free ◽  
Reaction Conditions ◽  
Rapid Synthesis ◽  
Short Reaction Time ◽  
Solvent Free Conditions ◽  
Solvent Free Reaction

A catalytic amount (2 mol %) of phosphotungstic acid (PTA) is sufficient to synthesize homoallylic alcohol in excellent yields from aldehyde with allyltributylstannane upon grinding under solvent-free reaction conditions. Easy handling, very short reaction time, solvent-free reaction conditions, and aqueous workup free isolation protocol may make our method very useful for synthetic chemists.

scholarly journals LiHSO4/SiO2as a New, Efficient and Reusable Catalytic System for the Chemoselective Conversion of Aldehydes to Acylals under Solvent-Free Conditions

2009 ◽  
Vol 6 (s1) ◽  
pp. S390-S396 ◽  
Author(s):  
Abdolkarim Zare ◽  
Alireza Hasaninejad ◽  
Esmael Rostami ◽  
Ahmad Reza Moosavi-Zare ◽  
Maria Merajoddin ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Acetic Anhydride ◽  
Catalytic System ◽  
Catalytic Amount ◽  
Significant Loss ◽  
Solvent Free ◽  
Reaction Conditions ◽  
Highly Efficient ◽  
Solvent Free Conditions

A highly efficient, green and expeditious solvent-free method is described for the chemoselective conversion of aldehydes to the corresponding acylals in excellent yields, using acetic anhydride in the presence of catalytic amount (20 mol%) of silica-supported LiHSO4. Ketones does not react under these reaction conditions. LiHSO4/SiO2can be recovered and reused without any significant loss of its catalytic activity.

scholarly journals Solvent-free synthesis of enantioenriched β-silyl nitroalkanes under organocatalytic conditions

2021 ◽  
Vol 17 ◽  
pp. 2642-2649
Author(s):  
Akhil K Dubey ◽  
Raghunath Chowdhury
Keyword(s):  
Temperature Control ◽  
Carbonyl Compounds ◽  
Room Temperature ◽  
Conjugate Addition ◽  
High Reactivity ◽  
Solvent Free ◽  
Reaction Conditions ◽  
Silyl Group ◽  
Solvent Free Conditions ◽  
Solvent Free Synthesis

An enantioselective 1,4-conjugate addition of nitromethane to β-silyl α,β-unsaturated carbonyl compounds catalyzed by bifunctional squaramide catalysts has been developed. This methodology offers both enantiomers of β-silyl nitroalkanes in good to excellent yields (up to 92%) and enantioselectivities (up to 97.5% ee) under solvent-free conditions at room temperature. Control experiments reveal that the presence of a β-silyl group in the enones is crucial for high reactivity under the optimized reaction conditions.

ZnO-nanorods Promoted Synthesis of α-amino Nitrile Benzofuran Derivatives using One-pot Multicomponent Reaction of Isocyanides

2020 ◽  
Vol 23 (4) ◽  
pp. 345-355
Author(s):  
Asef H. Najar ◽  
Zinatossadat Hossaini ◽  
Shahrzad Abdolmohammadi ◽  
Daryoush Zareyee
Keyword(s):  
Multicomponent Reaction ◽  
Room Temperature ◽  
Solvent Free ◽  
Primary Amines ◽  
Reusable Catalyst ◽  
Reaction Conditions ◽  
Trimethylsilyl Cyanide ◽  
Solvent Free Conditions ◽  
High Yields ◽  
Amino Nitrile

Aims & Objective: In this work ZnO-nanorod (ZnO-NR) as reusable catalyst promoted Strecker-type reaction of 2,4-dihydroxyacetophenone, isopropenylacetylene, trimethylsilyl cyanide (TMSCN), primary amines and isocyanides at ambient temperature under solvent-free conditions and produced α-amino nitriles benzofuran derivatives in high yields. These synthesized compounds may have antioxidant ability. Materials and Methods: ZnO-NRs in these reactions were prepared according to reported article. 2,4-dihydroxyacetophenone 1 (2 mmol) and isopropenylacetylene 2 (2 mmol) were mixed and stirred for 30 min in the presence of ZnO-NR (10 mol%) under solvent-free conditions at room temperature. After 30 min, primary amine 3 (2 mmol) was added to the mixture gently and the mixture was stirred for 15 min. After this time TMSCN 4 (2 mmol) was added to the mixture and stirred for 15 min. After completion of the reaction, as indicated by TLC, isocyanides 5 was added to mixture in the presence of catalyst. Results: In the first step of this research, the reaction of 2,4-dihydroxyacetophenone 1, isopropenylacetylene 2, methyl amine 3a, trimethylsilyle cyanide 4 and tert-butyl isocyanides 5a was used as a sample reaction to attain the best reaction conditions. The results showed this reaction performed with catalyst and did not have any product without catalyst after 12 h. Conclusion: In conclusion, we investigate multicomponent reaction of 2,4-dihydroxyacetophenone 1, isopropenylacetylene 2, primary amines 3, trimethylsilyl cyanide 4 and isocyanides along with ZnO-NRs as reusable catalyst at room temperature under solvent-free conditions which generates α-amino nitrile benzofuran derivatives in high yields. The advantages of our method are high atom economy, green reaction conditions, higher yield, shorter reaction times, and easy work-up, which are in good agreement with some principles of green chemistry. The compounds 8c exhibit excellent DPPH radical scavenging activity and FRAP compared to synthetic antioxidants BHT and TBHQ.

Al(OTf)3 — A highly efficient catalyst for the tetrahydropyranylation of alcohols under solvent-free conditions

2008 ◽  
Vol 86 (12) ◽  
pp. 1099-1104 ◽  
Author(s):  
Ahmed Kamal ◽  
M Naseer A Khan ◽  
Y VV Srikanth ◽  
K Srinivasa Reddy
Keyword(s):  
Comparative Study ◽  
Efficient Method ◽  
Catalytic Amount ◽  
Solvent Free ◽  
Molar Ratio ◽  
Reaction Conditions ◽  
Efficient Catalyst ◽  
Highly Efficient ◽  
Solvent Free Conditions ◽  
The Comparative Study

A simple and highly efficient method has been developed for the tetrahydropyranylation of alcohols by their reaction with 3,4-dihydro-2H-pyran (DHP) using a catalytic amount (0.01–1 mol%) of aluminium triflate under solvent-free conditions. The effect of various factors like temperature, amount of the catalyst, and molar ratio of substrates on the reaction conditions has also been studied. The comparative study of tetrahydropyranylation of benzyl alcohol using various catalysts including some reported ones shows the efficiency of this catalyst.Key words: tetrahydropyranylation, aluminium triflate, alcohols, catalysis.

scholarly journals Chemoselective Preparation of 1,1-Diacetates from Aldehydes, Mediated by a Keggin Heteropolyacid Under Solvent Free Conditions at Room Temperature

2007 ◽  
Vol 4 (1) ◽  
pp. 83-89 ◽  
Author(s):  
G. Romanelli ◽  
P. Dimitroff ◽  
P. Vázquez ◽  
J. C. Autino
Keyword(s):  
Acetic Anhydride ◽  
Efficient Method ◽  
Room Temperature ◽  
Catalytic Amount ◽  
Solvent Free ◽  
Solvent Free Conditions

A simple, general and efficient method has been developed for the conversion of aldehydes to 1,1-diacetates using acetic anhydride, a catalytic amount of non commercial Keggin heteropolyacid (H6PalMo11O40) (1% mol) in solvent free conditions at room temperature. Aromatic and aliphatic, simple and conjugated aldehydes were protected with excellent yields.

Iron (III) chloride hexahydrate as a highly efficient catalyst for acetylation of protic nucleophiles with acetic anhydride under solvent-free conditions

2020 ◽  
Vol 07 ◽  
Author(s):  
Naoures Jamel Eddine ◽  
Fayçal Jennen ◽  
Yakdhane Kacem ◽  
Jamil Kraiem
Keyword(s):  
Acetic Anhydride ◽  
Room Temperature ◽  
Catalytic Amount ◽  
Solvent Free ◽  
Environmentally Benign ◽  
Efficient Catalyst ◽  
Highly Efficient ◽  
Solvent Free Conditions ◽  
Chloride Hexahydrate ◽  
New Methodologies

Background: Acetylation of protic nucleophiles is used to protect these functional groups. Most of the methods described in the literature use solvents, one equivalent or more of toxic bases or expensive and toxic catalysts. Therefore, new methodologies are still in demand, above all, greener and more economical procedures. Objective: An eco-efficient method developed for acetylation of alcohols, phenols, thiols, amines and carbohydrates, using acetic anhydride and a catalytic amount of the environmentally benign and inexpensive FeCl3.6H2O under solvent free conditions. Methods: Acetylation of a variety of protic nucleophiles was performed using 0.2 mol % of FeCl3.6H2O as the catalyst, and 1.2 equiv. as the acetylating agent at room temperature and under solvent free conditions. Results: Our procedure appears to be highly efficient and promoted rapid and quantitative acetylation under simple and minimum manipulation. Chromatography or recrystallization were generally not necessary for the purification of products. Conclusion: This eco-friendly protocol appears to be potentially universally applicable in organic design to protect protic nucleophiles and potentially scalable for industrial fields.

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