Direct and Indirect Reductive Amination of Aldehydes and Ketones with Solid Acid Activated Sodium Borohydride under Solvent‐Free Conditions.

Abstract

Amines Q 0120 Direct and Indirect Reductive Amination of Aldehydes and Ketones with Solid Acid Activated Sodium Borohydride under Solvent-Free Conditions. -The process provides a simple, convenient, widely applicable, and environmentally friendly method to prepare diverse amines. -(CHO*, B. T.; KANG, S. K.; Tetrahedron 61 (2005) 24, 5725-5734; Dep. Chem., Hallym Univ., Chunchon 200-702, S. Korea; Eng.) -Jannicke 42-083

Synthesis and Evaluation of Novel 2-Pyrrolidone-Fused (2-Oxoindolin-3-ylidene)methylpyrrole Derivatives as Potential Multi-Target Tyrosine Kinase Receptor Inhibitors

“…Selective oxidation on α-methyl of 1 with ceric ammonium nitrate (CAN) at room temperature for 1 h quantitatively formed 2 , which bore an α-formyl functionality at the pyrrole ring. Compound 2 was then coupled with N , N -diethylethylenediamine, and then, without isolation, reduced directly with activated sodium borohydride/ p -toluenesulfonic acid in ethanol to obtain 3 in a satisfactory yield [ 25 ]. Ester 3 was hydrolyzed in methanol into carboxylic acid 4 .…”

Synthesis, characterisation, and antineoplastic cytotoxicity of hybrid naphthohydroquinone–nucleic base mimic derivatives

“…The 3-(4-methoxyphenylamino)propyl compound 2 and the 3-(pyridin-3-ylamino)propyl compound 3 were prepared by a direct solvent-free reductive amination reaction of the aldehyde 1 with 4-methoxyaniline or 3-aminopyridine and boric-acid-activated sodium borohydride. The reaction was carried out by grinding the mixture with an agate mortar and pestle at room temperature in air (Cho and Kang, 2005). To obtain the 3-(2-aminopyridin-3-ylamino)propyl derivative 4, the imine from 1 and 2,3-diaminopyridine was prepared in situ, either by refluxing with MgSO 4 in benzene or by microwave (MW) irradiation of the mixture adsorbed on montmorillonite K-10.…”

Reductive Amination of Aldehydes and Ketones Under Heterogeneous and Solvent-Free Conditions Using Sodium-Borohydride and Silica-Gel–Supported Sulfuric Acid

“…Similary aliphatic and cyclic ketones underwent this reaction to give the corresponding amines in excellent yield ( Table 2, entries [14][15][16][17][18][19][20]. However, to examine a greater range of amines to better illustrate the scope and limitation of the method, we have investigated the reaction with both primary and secondary amines, such as allylamine, piperidine, pyrrolidine, and morpholine, using PhCHO as representative aldehyde and cyclohexanone and 2-heptanone as representative ketones ( Table 2, entries [10][11][12][13][14][15][16][17][18][19][20]. Reductive amination of aliphatic aldehyde such as butanal with aniline, allyl amine, and piperidine also gave excellent yields of the corresponding amines ( Table 2, entries 21-23).…”

“…All these methods require stoichiometric or excess quantities of the hydrides, which are generally highly reactive and expensive. Other hydrides such as TiCl(OiPr) 3 -NaBH(OAc) 3 , [10] thiourea-Hantzsch ester, [11] Et 3 SiH-trifluoroacetic acid, [12] NaBH 4 Á H 3 BO 3 , [13] dibutylchlorotin hydride complex, [14] Zr(BH 4 ) 2 Cl 2 (dabco) 2 , [15] N-methyl piperidine zinc borohydride, [16] and NaBH 4 in micellar media [17] have also been used for this purpose. Of the commercially available metal hydrides, NaBH 4 has been used extensively for reduction of organic substrates because of environmental and economic considerations.…”