Cassia fistula galactomannan stabilized copper nanocatalyst as an efficient, recyclable heterogeneous catalyst for the fast clickable [3+2] Huisgen cycloadditions in water.

In this study, we have first time investigated the synthesis of copper nanocatalyst by using biopolymer galactomannan, naturally extracted from Cassia fistula pods. The methodology involved for the preparation of copper nanocatalyst is economical, efficient, environment friendly, and did not involve further processing for stabilization or reduction of copper nanoparticles. The morphology and structural characterization of the nanocatalyst was performed by using different techniques such as FT-IR, 1H NMR, SEM, EDX, HR-TEM, XRD, XPS, ICP-MS, BET, and TGA analysis. The prepared copper nanocatalyst is applied for the click [3+2] Huisgen cycloadditions of various azides and alkynes, employing water as environmentally benign solvent. In comparison to earlier reported methods, our method requires lowest catalyst loading, less reaction time, excellent yields and have wide substrate scope. Additionally, the catalyst was easily recovered by simple filtration and recycled at least ten consecutive times without any appreciable loss of efficiency and selectivity. The effect of mannose and galactose (Man/Gal) ratio of Cassia fistula galactomannan on the catalytic activity were also investigated.

Novel Functionalized Spiro [Indoline-3,5'-pyrroline]-2,2'dione Derivatives: Synthesis, Characterization, Drug-Likeness, ADME, and Anticancer Potential.

A highly stereo-selective, one-pot, multicomponent method was chosen to synthesize the novel functionalized 1, 3-cycloaddition spirooxindoles (SOXs) (4a-4h). Synthesized SOXs were analyzed for their drug-likeness and ADME parameters and screened for their anticancer activity. Our molecular docking analysis revealed that among all derivatives of SOXs (4a-4h), 4a has a substantial binding affinity (∆G) -6.65, -6.55, -8.73, and -7.27 Kcal/mol with CD-44, EGFR, AKR1D1, and HER-2, respectively. A functional study demonstrated that SOX 4a has a substantial impact on human cancer cell phenotypes exhibiting abnormality in cytoplasmic and nuclear architecture as well as granule formation leading to cell death. SOX 4a treatment robustly induced reactive oxygen species (ROS) generation in cancer cells as observed by enhanced DCFH-DA signals. Overall, our results suggest that SOX (4a) targets CD-44, EGFR, AKR1D1, and HER-2 and induces ROS generation in cancer cells. We conclude that SOX (4a) could be explored as a potential chemotherapeutic molecule against various cancers in appropriate pre-clinical in vitro and in vivo model systems.

N-Heterocyclic Carbene-Catalyzed Enantioselective [3 + 2] Annulation of Enals with Vinyl Ketones.

An unprecedented N-heterocyclic carbene (NHC)-catalyzed enantioselective [3 + 2] annulation of enals with vinyl ketones has been achieved. Unlike chalcones, the ß-unsubstituted enones, namely, vinyl ketones, have remained challenging in terms of reactivity, especially enantioselectivity. The disubstituted cyclopentenes were obtained in good yields and excellent stereoselectivities in the presence of Ti(OiPr)4.

Reductive Alkenylation of Ketimines via Hydride Transfer from Aldehydes.

The first direct N-heterocyclic carbene (NHC)-catalyzed preparation of allylic amines bearing a quaternary center (α-tertiary amine) from isatin-derived ketimines in the presence of vinyl selenones and aldehydes is reported. This multicomponent reaction is expected to proceed via unprecedented in situ reduction of imines through a hydride transfer from the aldehydes.

A General Method for α-Oxyacylation of Vinyl Ketones Using Koser's Reagent.

A direct general method for the preparation of α-oxyacylated vinyl ketones using Koser's hypervalent iodine reagent is reported. A variety of acyloxy groups from long-chain aliphatic, aromatic, α,ß-unsaturated carboxylic acids have been installed efficiently for the first time. The oxyacylated adducts were used for the preparation of densely functionalized chiral δ-lactones and cyclopentenes using carbene organocatalysis.

Stereoselective Oxidative Rearrangement of Disubstituted Unactivated Alkenes Using Hypervalent Iodine(III) Reagent.

The stereoselective oxidative rearrangement of disubstituted unactivated olefins has been achieved using a hypervalent iodine(III) reagent. The aryl group undergoes 1,2-migration to give tert-α-arylated aldehydes (as acetals). The preparation of these aldehydes/acetals, especially containing a tert-benzylic stereocenter, has remained challenging. This migration-based method provides a complementary approach over the known α-substitution-based methods for accessing this class of molecules.

Carbene/Base-Mediated Redox Alkenylation of Isatins using ß-Substituted Organoselenones and Aldehydes.

Achieving several desired transformations in a single operation remains one of the obvious goals in the synthetic organic chemistry. Herein we developed a multicomponent reaction for the preparation of alkenylated oxyindoles, bearing a quaternary alcohol-derived ester, via an NHC-catalyzed redox reaction in the presence of ß-substituted vinyl selenones and aldehydes.