A new mild base-catalyzed Mannich reaction of hetero-arylamines in water: highly efficient stereoselective synthesis of β-aminoketones under microwave heating

2009 ◽  
Vol 7 (7) ◽  
pp. 1410 ◽  
Author(s):  
Wen-Juan Hao ◽  
Bo Jiang ◽  
Shu-Jiang Tu ◽  
Xu-Dong Cao ◽  
Shan-Shan Wu ◽  
...  
Keyword(s):  
Microwave Heating ◽  
Mannich Reaction ◽  
Stereoselective Synthesis ◽  
Highly Efficient

Hafnium(IV) Chloride Catalyzes Highly Efficient Acetalization of Carbonyl Compounds

2019 ◽  
Vol 16 (6) ◽  
pp. 913-920 ◽  
Author(s):  
Israel Bonilla-Landa ◽  
Emizael López-Hernández ◽  
Felipe Barrera-Méndez ◽  
Nadia C. Salas ◽  
José L. Olivares-Romero
Keyword(s):  
Microwave Heating ◽  
Reaction Times ◽  
Protecting Groups ◽  
Catalyst Loading ◽  
Selective Protection ◽  
Highly Efficient ◽  
Aldehydes And Ketones ◽  
High Yields ◽  
Novel Catalyst ◽  
Acid Labile

Background: Hafnium(IV) tetrachloride efficiently catalyzes the protection of a variety of aldehydes and ketones, including benzophenone, acetophenone, and cyclohexanone, to the corresponding dimethyl acetals and 1,3-dioxolanes, under microwave heating. Substrates possessing acid-labile protecting groups (TBDPS and Boc) chemoselectively generated the corresponding acetal/ketal in excellent yields. Aim and Objective: In this study. the selective protection of aldehydes and ketones using a Hafnium(IV) chloride, which is a novel catalyst, under microwave heating was observed. Hence, it is imperative to find suitable conditions to promote the protection reaction in high yields and short reaction times. This study was undertaken not only to find a novel catalyst but also to perform the reaction with substrates bearing acid-labile protecting groups, and study the more challenging ketones as benzophenone. Materials and Methods: Using a microwave synthesis reactor Monowave 400 of Anton Paar, the protection reaction was performed on a raging temperature of 100°C ±1, a pressure of 2.9 bar, and an electric power of 50 W. More than 40 substrates have been screened and protected, not only the aldehydes were protected in high yields but also the more challenging ketones such as benzophenone were protected. All the products were purified by simple flash column chromatography, using silica gel and hexanes/ethyl acetate (90:10) as eluents. Finally, the protected substrates were characterized by NMR 1H, 13C and APCI-HRMS-QTOF. Results: Preliminary screening allowed us to find that 5 mol % of the catalyst is enough to furnish the protected aldehyde or ketone in up to 99% yield. Also it was found that substrates with a variety of substitutions on the aromatic ring (aldehyde or ketone), that include electron-withdrawing and electrondonating group, can be protected using this methodology in high yields. The more challenging cyclic ketones were also protected in up to 86% yield. It was found that trimethyl orthoformate is a very good additive to obtain the protected acetophenone. Finally, the protection of aldehydes with sensitive functional groups was performed. Indeed, it was found that substrates bearing acid labile groups such as Boc and TBDPS, chemoselectively generated the corresponding acetal/ketal compound while keeping the protective groups intact in up to 73% yield. Conclusion: Hafnium(IV) chloride as a catalyst provides a simple, highly efficient, and general chemoselective methodology for the protection of a variety of structurally diverse aldehydes and ketones. The major advantages offered by this method are: high yields, low catalyst loading, air-stability, and non-toxicity.

ChemInform Abstract: Stereoselective Synthesis of 1,2-Diamine Containing Indolines by a Conjugate Addition Nitro-Mannich Reaction.

ChemInform ◽  
2015 ◽  
Vol 46 (20) ◽  
pp. no-no
Author(s):  
James C. Anderson ◽  
Ian B. Campbell ◽  
Sebastien Campos ◽  
Jonathan Shannon ◽  
Derek A. Tocher
Keyword(s):  
Mannich Reaction ◽  
Stereoselective Synthesis ◽  
Conjugate Addition

Silver-assisted syntheses of fused five-membered N-heterocycles

2021 ◽  
Vol 25 ◽  
Author(s):  
Navjeet Kaur ◽  
Neha Ahlawat ◽  
Yamini Verma ◽  
Pooja Grewal ◽  
Pranshu Bhardwaj ◽  
...  
Keyword(s):  
Organic Chemistry ◽  
Heterocyclic Compounds ◽  
Stereoselective Synthesis ◽  
Review Article ◽  
Highly Efficient ◽  
Work Up ◽  
Detailed Work

: The metal-mediated formation of heterocycles is one of the most emerging and essential strategies in organic chemistry. The reactions utilized previously to synthesize heterocycles were less familiar to the scientists due to their detailed work-up, expensive nature, and complex operations. The silver-assisted cyclic reactions are highly efficient for both regioselective and stereoselective synthesis of five-membered fused N-heterocyclic compounds. The applications of silver in the preparation of five-membered fused N-heterocyclic compounds are covered in this review article.

An asymmetric acetate-Mannich reaction of chiral isatin derived ketimines and its applications

2017 ◽  
Vol 15 (43) ◽  
pp. 9217-9225 ◽  
Author(s):  
Saumen Hajra ◽  
Suhas Shivajirao Bhosale ◽  
Atanu Hazra
Keyword(s):  
Amino Acid ◽  
Mannich Reaction ◽  
Direct Synthesis ◽  
Highly Efficient ◽  
Excellent Selectivity

A highly efficient TMSOTf-mediated asymmetric acetate-Mannich reaction of chiral isatin derived ketimines and S-phenyl thioacetate was developed to afford the direct synthesis of indole-based β3,3-amino acid thioester with excellent selectivity (dr > 98 : 2). Syntheses of (+)-AG-041R and 3-aminopyrroloindoline have been accomplished utilizing the method.

ChemInform Abstract: Yb(OiPr)3, a Highly Efficient Catalyst for the Nitro-Mannich Reaction.

ChemInform ◽  
2010 ◽  
Vol 32 (37) ◽  
pp. no-no
Author(s):  
Changtao Qian ◽  
Feifeng Gao ◽  
Ruifang Chen
Keyword(s):  
Mannich Reaction ◽  
Efficient Catalyst ◽  
Highly Efficient

Organometallic titanocene complex as highly efficient bifunctional catalyst for intramolecular Mannich reaction

2019 ◽  
Vol 33 (7) ◽  
Author(s):  
Yunyun Wang ◽  
Yajun Jian ◽  
Ya Wu ◽  
Huaming Sun ◽  
Guofang Zhang ◽  
...  
Keyword(s):  
Mannich Reaction ◽  
Bifunctional Catalyst ◽  
Highly Efficient
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