The
synthesis and characterization of a mixed ligand metal–organic
framework (MOF) with good thermal and chemical stability, {[Co(BDC)(L)·2H2O]·xG}
n
(CoMOF-2), involving
an aromatic dicarboxylate (H2
BDC = 1,4-benzenedicarboxylic
acid) and an acyl-decorated N-donor linker [L = (E)-N′-(pyridin-4-ylmethylene) isonicotinohydrazide]
by various physicochemical techniques, including Single crystal X-Ray
Diffraction (SXRD), are reported. The MOF showed a good affinity for
CO2 capture, and Grand Canonical Monte Carlo simulation
studies exposed strong interactions of CO2 with the functionalized
N-donor ligand of the framework. CoMOF-2 and KI act as
an efficient binary catalyst for the sustainable utilization of CO2 with spiro-epoxy oxindole to spirocyclic carbonate under
ambient conditions. Notably, herein we report MOF-based catalysis
for the cycloaddition of oxindole-based epoxides with CO2 for harvesting new spirocyclic carbonates. Interestingly, we could
isolate and crystallize six of the spirocyclic carbonate products,
and the structure of the newly synthesized molecules has been established
by SXRD analysis. We present a plausible proposed catalytic mechanism
through activation of the epoxide ring by the Lewis acidic/basic sites
present on the framework surface that is validated by molecular modeling.
Developing a strategy
to synthesize an unprecedented and previously
unknown organic molecule is especially appealing. The design, synthesis,
and development of a new class of spiro-cyclic carbonates are reported.
An efficient process involving the cycloaddition reaction of spiro-epoxyoxindoles
with CO2 (balloon) has been demonstrated using deep eutectic
solvent (DES). The reaction can be carried out under mild reaction
conditions to afford desired spiro-cyclic carbonates in excellent
yields (up to 98%). The product could be separated easily, and the
DES was reusable four times with retention of its activity.
New chiral macrocyclic cobalt(III) salen complexes were synthesized and used as catalyst for the asymmetric kinetic resolution (AKR) of terminal epoxides and glycidyl ethers with aromatic/aliphatic amines and water as nucleophiles. This is the first occasion where a Co(III) salen complex demonstrated its ability to catalyze AKR as well as hydrolytic kinetic resolution (HKR) reactions. Excellent enantiomeric excesses of the epoxides, the corresponding amino alcohols and diols (upto 99%) with quantitative yields were achieved by using the chiral Co(III) salen complexes in dichloromethane at room temperature. This protocol was further extended for the synthesis of two important drug molecules, i.e., (S)‐propranolol and (R)‐naftopidil. The catalytic system was also explored for the synthesis of chirally pure diols and chiral cyclic carbonates using carbon dioxide as a greener renewable C1 source. The catalyst was recycled for upto 5 catalytic cycles with retention of enantioselectivity.magnified image
The advent of saturated N-heterocycles as valuable building blocks in medicinal chemistry has led to the development of new methods to construct such nitrogen-containing cyclic frameworks. Despite the apparent strategic...
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