The synthesis of life saving drug molecules in a cost-effective and environmentally benign pathway is of paramount significance. We present an environment friendly protocol to prepare core moieties of top selling drug molecules such as boscalid and telmisartan using Suzuki−Miyaura coupling conditions. In contrast to the traditional synthesis of these pharmaceutically important molecules, we have accomplished a graphite oxide (GO) supported palladium nanoparticles (PdNPs) based catalyst which quantitatively produced these core biaryl moieties of top selling drug molecules in a recyclable way. The catalytic activity remained unchanged even after 16 successive catalytic cycles without incorporating any palladium metal impurity in the pharmaceutically significant organic products. A detailed study including IR spectroscopy, solid state NMR spectroscopy, X-ray photoelectron spectroscopy, and DFT calculation was employed to understand the role of solid support on the nondecaying recycling ability of the catalyst during the Suzuki−Miyaura coupling reaction. The study indicates a strong chemical interaction of the different functionalities present in the GO, with the palladium centers which is primarily responsible for such sustained catalytic activity during the consecutive Suzuki−Miyaura coupling cycles.
Open-shell phenalenyl chemistry has widely been explored in the last five decades demonstrating its potential in various applications including molecular switch, spin memory device, molecular battery, cathode material, etc. In this article, we have explored another new direction of open-shell phenalenyl chemistry toward transition metal-free catalytic C-H functionalization process. A phenalenyl ligand, namely, 9-methylamino-phenalen-1-one (4a), promoted chelation-assisted single electron transfer (SET) process, which facilitates the C-H functionalization of unactivated arenes to form the biaryl products. The present methodology offers a diverse substrate scope, which can be operated without employing any dry or inert conditions and under truly transition metal based catalyst like loading yet avoiding any expensive or toxic transition metal. This not only is the first report on the application of phenalenyl chemistry in C-H functionalization process but also provides a low-catalyst loading organocatalytic system (up to 0.5 mol % catalyst loading) as compared to the existing ones (mostly 20-40 mol %), which has taken advantage of long known phenalenyl based radical stability through the presence of its low-lying nonbonding molecular orbital.
VII. Optimisation study for the reduction of4-methyl-N-(1-phenylethylidene)aniline....S14 VIII. General procedure for catalytic hydrosilylation of ketimines to secondary amines and characterization data.
This
study reports the metal-free formylation of amides using carbon
dioxide under ambient conditions. An abnormal N-heterocyclic carbene
(aNHC) acts as an efficient catalyst for the formylation
of amides in the presence of hydrosilane at room temperature. This
methodology enables the formation of a C–N bond and can be
utilized in building up core moieties of two natural products having
strong larvicidal activity such as alatamide and lansiumamide A. A preliminary mechanistic picture for this
transformation has been proposed through isolation of reaction byproduct
(confirmed by single crystal X-ray study) as well as by characterizing
intermediates with spectroscopy.
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