Mild and Efficient Reductive N,N-Dimethylation of Amines by Using 1,3-Dimethylimidazole-2-ylidene Borane (diMe-Imd-BH 3 (original) (raw)
Related papers
ChemistrySelect 2022 Haque Mild and Efficient Reductive N N‐Dimethylation of Amines by Using 1 (1)
Herein, we report a new, simple, one pot and chemoselective method for N-methylation and N,N-dimethylation of aliphatic and aromatic amines under ambient conditions using NHCborane i.e 1,3-dimethylimidazole-2-ylidene borane (diMe-Imd-BH 3 ), as reducing agent. The present strategy has significant advantages like mild reaction conditions, quick and effortless work-up processes, and the use of non-toxic inexpensive reagents. The amines with acid-sensitive moieties are also methylated successfully.
Http Dx Doi Org 10 1080 00397910801997769, 2008
General Methods Reagents were purchased from commercial suppliers and were used without purification unless otherwise noted. Anhydrous tetrahydrofuran was purchased from Fluka Chemika. Dibutyltin dichloride (96%) was purchased from Aldrich Chemical Company. All reactions were performed in borosilicate test tubes with magnetic stirring. Reactors were assembled open to the air, and placed under nitrogen after the addition of all reagents. Chromatography was performed using manual injection on an ISCO SQ16 chromatograph with 10 g prepacked RediSep silica cartridges, and gradients of either ethyl acetate-hexane (anilines) or 2 M methanolic ammonia-dichloromethane (alkylamines). 1 H and 13 C NMR spectra were recorded on a Bruker spectrometer. Chemical shifts are reported in parts per million downfield from an internal Me 4 Si standard. In cases where reactions were monitored by 1 H NMR, samples were prepared by dissolving an aliquot of the crude reaction mixture (approx. 0.04 mL) in CDCl 3 (approx. 1 mL). Melting points are uncorrected and were obtained on a MelTemp apparatus. Combustion analyses were performed by Desert Analytics. Representative Procedure for the Reductive Amination of 4-Methoxybenzaldehyde with Aniline A solution of 4-methoxybenzaldehyde (0.18 mL, 1.5 mmol, 1.0 eq) in THF (0.3 mL) was treated with aniline (0.14 mL, 1.5 mmol, 1.0 eq) and dibutyltin dichloride (9 mg, 3x10-2 mmol, 0.02 eq). The resulting yellow solution was allowed to stir for 2 min, and treated with phenylsilane (0.20 mL, 1.7 mmol, 1.1 eq). After 2 h, thin layer chromatography showed no remaining aniline. The colorless reaction was diluted with
Recent Development on Catalytic Reductive Amination and Applications
Current Organic …, 2008
Reductive amination is one of the most useful and versatile methods for the preparation of' amines in biological and chemical systems. The present review focuses on the development of catalytic reductive amination from beginning to recent ones, where we attempted to thoroughly illustrate an account of utility of various reagents including organocatalyst, symmetric and asymmetric (Ru, Rh, Ir) complexes, boron, tin or silicon reagents etc for enantio-and/or chemoselective reactions under different reaction conditions with emphasis on the yields of the reaction products and stability of the reagents used. Emerging applications of this reaction for the development of chiral ligands, pharmacologically active molecules, combinatorial scaffold, and key step in the total synthesis of some interesting natural products is also reviewed briefly.
Hitchhiker’s Guide to Reductive Amination
Synthesis, 2019
A comparative study of various widely used methods of reductive amination is reported. Specifically, such reducing agents as H2, Pd/C, hydride reagents [NaBH4, NaBH3CN, NaBH(OAc)3], and CO/Rh2(OAc)4 system were considered. For understanding the selectivity and activity of the reducing agents reviewed herein, different classes of starting materials were tested, including aliphatic and aromatic amines, as well as aliphatic and aromatic aldehydes and ketones. Most important advantages and drawbacks of the methods, such as selectivity of the target amine formation and toxicity of the reducing agents were compared. Methods were also considered from the viewpoint of green chemistry.
NaBH4/Ga(OH)3: An efficient reducing system for reductive amination of aldehydes
Oriental Journal of Chemistry, 2013
Amines are important functionalities in active pharmaceutical intermediates and drugs.The reduction of nitro, cyano, azide, carboxamide compounds and alkylation of amines are common routes for the synthesis of amines. These methodologies for secondary amines are often problematic because of harsh reaction conditions, overalkylation, low chemical selectivity and generally poor yields. Therefore, there is a specific interest in developing controlled synthesis of secondary amines due to its vast applications. Other approach is reductive amination reaction in a single operationi.e direct reductive amination (DRA). Reductive aminationcan be carried out by amination of carbonyl compounds with sodiumborohydride under different reducing
Single Nucleotide-Catalyzed Biomimetic Reductive Amination
Advanced Synthesis & Catalysis, 2010
We have successfully developed a single nucleotide (adenosine 5'-diphosphate)-catalyzed enantioselective direct reductive amination of aldehydes and ketones using a Hantzsch ester as reducing agent. The process is a simple, efficient and a real mimic of the NADH reduction approach for the synthesis of structurally diverse amines. This reaction is the first report demonstrating the ability of a single nucleotide as catalyst and one of the most genuine biomimetic reactions of organic chemistry.