<p><a></a><a>The development
of Earth-abundant reusable and no-toxic heterogeneous catalyst applied in the
pharmaceutically, bio-active relevant compounds synthesis as well as other
organic syntheses still remains as the most important goal of the general
chemical research. N-methylated compounds, as one of the most essential
bioactive compounds,</a> have been
widely used in the fine and bulk industries for the production of high-value
chemicals including pharmaceuticals, agrochemicals, and dyes. As their reports, activated toxic methyl iodide and dimethyl
sulfoxide were usually employed in the traditional N-methylation, which easily
suffer from narrow scopes of amines, generation of by-products, and a large
amount of waste. <a>Very recently, </a>transition metal-catalyzed methylation
of amines has become an efficient, practical, and cost-effective method for the
one-pot selective synthesis of N-methylamines with C<sub>1</sub> sources. Herein, we first
developed a simple and <a>environmentally friendly</a> method
for the preparation of efficient, reusable, and low-cost graphene spheres
encapsulated Ni/NiO nanoalloy catalysts (Ni/NiO@C) for highly selective
synthesis of the N-methylated compounds by using various functional amines and
aldehydes under easily
handle-able and industrially <a></a><a>applicable </a>conditions.<b> </b>A large number of primary, secondary
amines (more than 70 examples) could be converted smoothly to the corresponding
N, N-dimethylamines with the participation of different functional aldehydes.
The gram-scale synthesis was also demonstrated in an excellent yield; not only
that, the catalyst was further proved that it could be easily recycled by its
intrinsic magnetism and reused up to ten times without losing activity and
selectivity. Both of them are the great advantages in contrast to other
catalysts reported previously. And also, for the first time, we have developed
the highly efficient, cost-effective tandem synthesis of N, N-dimethylamines products in a one-pot
process by means of aldehydes and NH<sub>3</sub>. As far as we know, this is
the first example of the synthesis of tertiary
amines with the combined reaction process of reductive
amination of aldehydes and N-methylation of primary amines only with the single
one earth-abundant metal catalyst. Overall, the
advantages of this newly developed method including operational simplicity,
high stability, easily recyclable, cost-effective of the catalyst, and good
functional group compatibility for the synthesis of N-methylation products, as well as the
highly efficient and industrial applicable tandem synthesis process.</p>
Selective Synthesis of Secondary Amines via N-Alkylation of Primary Amines and Ammonia with Alcohols by Supported Copper Hydroxide Catalysts
