16 Green Economy Approach to Develop Bioactive …
407
conversion) for substitution of benzyl bromide when compared with non-supported
catalysts (71% conversion) [64]. A silica-coated magnetic iron oxide nanoparticles
(Fe 3 O 4 /SiO 2 ) supported by pyrimidine-2,4-diamine (PDA) were used as efficient
nano catalyst for synthesis of 1,4-dihydropyridine (1,4-DHP) derivatives, as one
of the most important pharmaceutical compounds. Vibrating sample magnetometer
(VSM) analysis showed the super paramagnetic property exhibited by these nano
catalysts which support the easy separation of nano catalyst from reaction mixture.
The PDA functionalized silica-coated MNPs displayed good catalytic activity for
1,4-DHP analogues synthesis even after seven times cycling. The production yield
was about 89–73% up to seven cycles, respectively. Therefore, Fe 3 O 4 /SiO 2 -PDA
catalyst is reusable and recyclable up various reaction cycles with small reduction
in production yield due to probably agglomeration or some loss of catalyst particles
during separation [65].
The catalytic synthesis of pyrido [2,3-d] pyrimidines was carried out for first time
with the help of recyclable and reusable nano-magnetic silica-bonded S-sulfonic acid
(Fe 3 O 4 @SiO 2 @(CH 2 ) 3 S–SO 3 H) catalyst. It was observed that after several reaction
cycles the Fe 3 O 4 @SiO 2 @ (CH 2 ) 3 S–SO 3 H catalyst did not lose its catalytic efficiency
and was easily recovered after each cycle separation. Up to eight times reaction runs,
the production yield was obtained in the range of 81–92% which verifies that MNP
supported catalysts are promising future for pharmaceutical industries as they are
economically and environmentally strong catalysts [66].
Poly-hydroquinoline analogues (PHQa) could be synthesized by using MNPs as
eco-friendly catalysts. Ni–Cu–Mg–Fe 2 O 4 MNPs using tragacanth gum by the sol-gel
method is an effective catalyst for synthesis of (PHQa) via multi-component reactions under microwave irradiation. It was well reported that Ni–Cu–Mg–Fe 2 O 4 MNPs
provide good PHQa yield (98%) with less reaction time (4 min) when compared with
other chemical methods. This was because of good magnetic nature (27.85 emu/g)
present in Ni–Cu–Mg–Fe 2 O 4 MNPs which facilitate its separation process [67].
Moreover, the easy recovery of this catalyst after each reaction cycle provides an
opportunity for its reuse in further cycles, clearly demonstrates the low cost of the
obtained drug. The triazoles heterocycles derivatives are commonly used as antiviral
and antibacterial agents and due to these medicinal properties, the synthesis of triazoles derivatives is well documented in various reports. Cu(I) based catalysts are
most commonly used in the synthesis of triazoles heterocycles but these methods are
not so efficient because Cu compounds could not be completely separated from the
reaction mixture and the traces remains under physiological conditions [68]. Due to
high reactivity and toxicity, Cu(I) can impart very harmful effects on living organism.
Therefore, to remove the Cu(I) from reaction media, the immobilization of Cu(I) is
carried out on various MNPs.
Sadjadi et al. developed a heterogeneous catalyst h-Fe 2 O 3 @SiO 2 -CDNS by amine
fictionalization of magnetic Fe 2 O 3 hollow spheres which was further grafted with
Cl-functionalized cyclodextrin CDNS-Cl, covalently. The resulting hybrid system
was then used as a support for Pd(0) nanoparticles immobilization and referred
as Pd@ h-Fe 2 O 3 @SiO 2 -CDNS nano catalyst, easy magnetically separated. The
407
conversion) for substitution of benzyl bromide when compared with non-supported
catalysts (71% conversion) [64]. A silica-coated magnetic iron oxide nanoparticles
(Fe 3 O 4 /SiO 2 ) supported by pyrimidine-2,4-diamine (PDA) were used as efficient
nano catalyst for synthesis of 1,4-dihydropyridine (1,4-DHP) derivatives, as one
of the most important pharmaceutical compounds. Vibrating sample magnetometer
(VSM) analysis showed the super paramagnetic property exhibited by these nano
catalysts which support the easy separation of nano catalyst from reaction mixture.
The PDA functionalized silica-coated MNPs displayed good catalytic activity for
1,4-DHP analogues synthesis even after seven times cycling. The production yield
was about 89–73% up to seven cycles, respectively. Therefore, Fe 3 O 4 /SiO 2 -PDA
catalyst is reusable and recyclable up various reaction cycles with small reduction
in production yield due to probably agglomeration or some loss of catalyst particles
during separation [65].
The catalytic synthesis of pyrido [2,3-d] pyrimidines was carried out for first time
with the help of recyclable and reusable nano-magnetic silica-bonded S-sulfonic acid
(Fe 3 O 4 @SiO 2 @(CH 2 ) 3 S–SO 3 H) catalyst. It was observed that after several reaction
cycles the Fe 3 O 4 @SiO 2 @ (CH 2 ) 3 S–SO 3 H catalyst did not lose its catalytic efficiency
and was easily recovered after each cycle separation. Up to eight times reaction runs,
the production yield was obtained in the range of 81–92% which verifies that MNP
supported catalysts are promising future for pharmaceutical industries as they are
economically and environmentally strong catalysts [66].
Poly-hydroquinoline analogues (PHQa) could be synthesized by using MNPs as
eco-friendly catalysts. Ni–Cu–Mg–Fe 2 O 4 MNPs using tragacanth gum by the sol-gel
method is an effective catalyst for synthesis of (PHQa) via multi-component reactions under microwave irradiation. It was well reported that Ni–Cu–Mg–Fe 2 O 4 MNPs
provide good PHQa yield (98%) with less reaction time (4 min) when compared with
other chemical methods. This was because of good magnetic nature (27.85 emu/g)
present in Ni–Cu–Mg–Fe 2 O 4 MNPs which facilitate its separation process [67].
Moreover, the easy recovery of this catalyst after each reaction cycle provides an
opportunity for its reuse in further cycles, clearly demonstrates the low cost of the
obtained drug. The triazoles heterocycles derivatives are commonly used as antiviral
and antibacterial agents and due to these medicinal properties, the synthesis of triazoles derivatives is well documented in various reports. Cu(I) based catalysts are
most commonly used in the synthesis of triazoles heterocycles but these methods are
not so efficient because Cu compounds could not be completely separated from the
reaction mixture and the traces remains under physiological conditions [68]. Due to
high reactivity and toxicity, Cu(I) can impart very harmful effects on living organism.
Therefore, to remove the Cu(I) from reaction media, the immobilization of Cu(I) is
carried out on various MNPs.
Sadjadi et al. developed a heterogeneous catalyst h-Fe 2 O 3 @SiO 2 -CDNS by amine
fictionalization of magnetic Fe 2 O 3 hollow spheres which was further grafted with
Cl-functionalized cyclodextrin CDNS-Cl, covalently. The resulting hybrid system
was then used as a support for Pd(0) nanoparticles immobilization and referred
as Pd@ h-Fe 2 O 3 @SiO 2 -CDNS nano catalyst, easy magnetically separated. The