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Anefficient method for the preparation of 5,6-dihydropyrazolo[1,5-c]quinazolines via gold(I)-catalyzed chemoselectivebicyclization of N-propargylic sulfonylhydrazoneshas been developed. This process relies on the chemoselective cyclizationof the hydrazone nitrogen instead of the usually favored aniline nitrogenonto the alkyne. The synthetic utility of the current strategy isdemonstrated through the synthesis of a potential Eg5/Kinesin spindleprotein inhibitor. [ABSTRACT FROM AUTHOR]

A highly efficient Pt-catalyzed [3,3]sigmatropic rearrangement/cyclizationcascade of N-propargylhydrazones is reported.The process provides expedient access to a variety of highly functionalizedpyrazoles. The substrate has good substituted group compatibility,and the bioactive 3-CF3pyrazoles could be synthesizedeasily with this method. [ABSTRACT FROM AUTHOR]

CO 2 is an important C1 resource. We report a method for the synthesis of pharmacologically active 2-oxazolidinones by reacting CO 2 with allylic amines. As opposed to previous addition reactions, the unsaturated double bonds are preserved. Thus, the product is more plastic and easier to use for subsequent structural modification. Furthermore, this method can also be applied to the synthesis of six-membered heterocycles (1,3-oxazinan-2-ones) and the participation of a low concentration of CO 2 , indicating it has certain practicability.

The study reported an electrochemically mediated method for the preparation of 2,1-benzoxazoles from o -nitrophenylacetylenes. Different from the traditional electrochemical reduction of nitro to nitroso, the nitro group directly underwent a cyclization reaction with the alkyne activated by selenium cation generated by the anodic oxidation of diphenyl diselenide and finally produced the desired products.

C-centered radical cyclization under electrochemical conditions is a feasible strategy for constructing cyclic structures. Reported herein is the electrochemical synthesis of highly functionalized 1-naphthols using alkynes and 1,3-dicarbonyl compounds by (4 + 2) annulation of C-centered radical. Electrolysis was conducted with Cp 2 Fe as redox catalyst, thereby eliminating the use of oxidants and transition-metal catalysts. The synthesized 1-naphthol compounds showed good antitumor activity in vitro, and further studies indicated that compound 3bl induced tumor cell apoptosis.

We developed an electrochemically enabled dehydrogenative annulation reaction of amides and alkynes for the synthesis of antitumor polycyclic isoquinolinones through a double C-H activation route. No external oxidant is required in this reaction, and electricity is used for Ru catalyst circulation. The most remarkable feature of this reaction is the effective improvement of product regioselectivity under mild electrolytic conditions in comparison with previously set strong oxidant conditions.

An efficient strategy for the synthesis of benzofuro[2,3- b]pyrazines was developed. These tricyclic scaffolds were formed through a multistep cascade sequence, which includes double insertion of isonitriles and chemoselective bicyclization. In this reaction, a nanopalladium was used as a recyclable catalyst. Product 3w exhibited excellent anticancer activity toward T-24 (IC 50 = 12.5 ± 0.9 μM) and HeLa (IC 50 = 14.7 ± 1.6 μM) cells. We also explored the action mechanism of 3w on T-24 cells.

Two types of thiazole derivatives are synthesized through a multistep cascade sequence with Pd-metalated phosphorus-doped porous organic polymers (POPs) as heterogeneous catalysts. The POPs could be used as both ligands and catalyst supports. No obvious aggregation and loss of any catalytic activity of the catalysts were observed after 10 runs of the reaction. More importantly, imidazo[4,5- d]thiazoles, which are a new class of thiazole derivatives, could be obtained through K 2 CO 3 -promoted intramolecular cyclization of the synthesized polysubstituted thiazoles. Furthermore, the in vitro anticancer activity of these new compounds were tested with MTT assay, and compound 4b exhibited good antitumor activity toward T-24 and A549 cells with IC 50 values of 10.3 ± 0.8 and 11.8 ± 0.5 μM, respectively. In addition, the action mechanism of 4b on tumor cells was determined.

A simple and efficient Cu-catalyzed decarboxylative/click reaction for the preparation of 1,4-disubstituted 5-arylselanyl-1,2,3-triazoles from propiolic acids, diselenides, and azides has been developed. The mechanistic study revealed that the intermolecular AAC reaction of an alkynyl selenium intermediate occurred. The resulting multisubstituted 5-seleno-1,2,3-triazoles were tested for in vitro anticancer activity by MTT assay, and compounds 4f, 4h, and 4p showed potent cancer cell-growth inhibition activities.

A highly efficient AgOTf catalyzed [3,3] sigmatropic rearrangement/1,3-H shift/6π aza-electrocyclization cascade reaction of N-propargylic hydrazones has been developed. This method provides a new mild synthetic route to various polysubstituted 1,6-dihydropyridazines including the 3-CF3-substituted ones with high selectivity.

A novel method for the preparation of 5,6-dihydropyrazolo[5,1-a]isoquinoline via indium(III)-promoted halocyclizations of N-propargylic sulfonylhydrazones has been developed. The pyrazole and 3,4-dihydroisoquinoline moieties were synchronously formed via a cascade cyclization reaction using easily assembled open-chain compounds. The pyrazole and 3,4-dihydroisoquinoline moieties were formed via a cascade cyclization reaction using easily assembled open-chain compounds.

An efficient gold-catalyzed cyclization/arylidene group transfer cascade reaction of N-propioloyl hydrazones has been developed. This method provides a novel approach for the synthesis of various functionalized 4-arylidenepyrazolones.