A Homocoupling Approach to the Key Dione of CyMe4-BTPhen – Vital Ligands for Nuclear Clean-Up by the SANEX Process

CyMe4-BTPhen and CyMe4-BTBP are the principal ligand systems used in Europe for the separation of actinides from lanthanides as a part of the SANEX process for nuclear recycling and reprocessing. We present a new approach to the synthesis of the CyMe4-fragment beginning from readily available hydroxypivalic acid. It features a cobalt-catalysed homocoupling of a neopentyl bromide to provide the key bis-ester precursor, thereby avoiding the requirement for technically challenging low temperature LDA-mediated aldol chemistries.

Synthesis of [1,4]Oxathiepino[5,6-b]quinolines via Base-Mediated Intramolecular Hydroalkoxylation

A base-mediated intramolecular hydroalkoxylation that was used to prepare a series of seven-membered S,O-heterocycles is described. 2-Thiopropargyl-3-hydroxymethyl quinolines were prepared starting from 2-mercaptoquinoline-3-carbaldehydes, via S-propargylation and reduction of a formyl group. Interestingly, 2-mercaptopropargyl-3-hydroxymethyl quinolines were converted into the corresponding oxathiepinoquinolines in the presence of t-BuOK. It is proposed that the S-propargyl moiety, in the presence of base, is converted into its allenyl isomer; subsequent addition of a hydroxyl group to the terminal double bond yields the 3-methyl-5H-[1,4]oxathiepino[5,6-b]quinoline in good to high yield. Notably, the procedure is adaptable to the conversion of N-propargyl indole-2-methanol into the corresponding intramolecular hydroalkoxylation product.

Synthesis and Molecular Docking Studies of N,N-Dimethyl Arylpyranopyrimidinedione Derivatives

The synthesis of N,N-dimethyl arylpyranopyrimidinedione derivatives from aromatic aldehydes, N-methyl-1-(methylthio)-2-nitroethamine (NMSM) and 1,3-dimethyl barbituric acid, in the presence of piperidine as a catalyst, is reported. The reaction mechanism involves a Knoevenagel condensation, followed by Michael addition and intramolecular O-cyclization reaction sequence. The synthesized compounds were docked with human kinesin Eg5 protein to calculate binding energy, inhibition constant and H-bond interaction. All the compounds show good binding affinity towards the protein, with significant docking score.

Efficient Synthesis of Isoquinoline Derivatives through Sequential Cyclization–Deoxygenation Reaction of 2-Alkynylbenzaldoximes

We describe a novel, simple, robust, and efficient cyclization/deoxygenation approach for the synthesis of functionalized isoquinoline derivatives. Over the course of continued studies on o-alkynylbenzaldoxime cyclization reactions, the formation of cyclic nitrones through 6-endo-dig cyclization was achieved using silver triflate or bromine as an electrophile, and subsequently, the deoxygenation process was carried out in the presence of CS2 in good to high yields.

Oxidative Annulation of Diphenylpropanamides via In Situ Hypervalent Iodine-Promoted Intramolecular C–N/C–O Bond Formation

An aryl iodide catalyzed intramolecular oxidative transformation of diphenylpropanamide derivatives is described that can readily afford the C–N/C–O coupling products in a single step. The speed of the 1,3-aryl iodide migration process determines the diversity of target compound generation in this reaction. This straightforward approach can be performed with the use of inexpensive and readily available catalyst, transition-metal-free, mild conditions and good functional group tolerance.

Mild biamidine transfer conditions for the synthesis of aliphatic biguanides

This study focuses on the development of new synthetic pathways to monosubstituted biguanides from amines. An exhaustive comparison of the conditions and reagents used for biamidine transfer was performed. New reagents were synthesized and optimized conditions for the synthesis of substituted biguanides under mild conditions were developed. Eventually, two high-yielding and straightforward protocols for the transfer of a biamidine group to various amines are proposed and their scope and limitations have been explored. These conditions include: i) a direct chromatography-free procedure and ii) an eco-friendly procedure in water compatible with bio-inspired molecules. They are particularly efficient for the demanding conversion of aliphatic amines.

Intramolecular Oxidative Diaryl Coupling of Tetrasubstituted Diphenylamines for Preparation of Bis(trifluoromethyl) Dimethyl Carbazoles

Synthetic preparation of carbazoles can be challenging, requiring ring building strategies and/or precious metal catalysts. Presented herein is a method for preparation of carbazoles with the use of inexpensive and reliable hypervalent iodine chemistry. An oxidative single electron transfer (SET) event initiates cyclization for preparation of our trifluoromethyl carbazoles. This method has been shown to be useful for a variety of bis(trifluoromethyl)carbazole isomers that are of primary interest for use as battery materials.

Ru-Catalyzed Selective C–H Functionalization of Pyridotriazoles with Acrylates

Ruthenium-catalyzed efficient and selective C–H alkenylation of pyridotriazoles with acrylates is described. The combination of metals (Ru and Fe) plays a crucial role in achieving quantitative yields of the desired products. The reaction is proposed to involve the formation of a ruthenium cyclometalated intermediate.

Asymmetric Sequential Michael Addition and Cyclization Reactions of 2-(2-Nitrovinyl)phenols Catalyzed by Bifunctional Amino-Squaramides

In this work, we describe the Michael addition–cyclization reaction of 2-(2-nitrovinyl)phenol with two different reactive Michael donors, which lead to chiral benzopyran derivatives. Specifically, bifunctional amino-squaramides with one or two chiral units in the side chains were evaluated as catalysts in these transformations. Furthermore, the utility of selected green solvents as reaction media for these processes was also tested. The best result was achieved with methyl-cyclopentanone-2-carboxylate as the Michael donor in ethyl (–)-l-lactate with quinine-based amino-squaramide as catalyst (yield 72%, dr >99:1, ee 99%).

Trichloroacetamidate Triggered Expeditious and Novel Synthesis of N-Acylbenzotriazoles

A facile route for the synthesis of diverse range of N-acylbenzotriazole derivatives from corresponding carboxylic acids has been established through carbonyl activation pathway. In this method, trichloroacetonitrile is performed as an effective reagent for an easy access of N-acylbenzotriazoles which was simply proceed through the activation of carboxylic acids via in situ imidate formation in anhydrous 1,2 dichloroethane followed by addition of 1H-benzotriazole at 80 oC for 3-4 hours. Easy handling, one-pot, and metal-free condition demonstrate the notable merits of the devised protocol.