Asymmetric Formal (3 + 2) Cyclocondensation of Coumarin-3-Formylpyrazoles as 3-Carbon Partners with 3-Hydroxyoxindoles via Esterification/Michael Addition Sequence.

The first enantioselective formal (3 + 2) cyclocondensation involving α,β-unsaturated pyrazoleamides as 3-carbon partners was accomplished in a stepwise fashion. The stepwise esterification/Michael addition sequence is promoted by Zn(OTf) and quinine-squaramide derivative, respectively. The protocol enables access to spiro-fused pentacyclic spirooxindoles from coumarin-3-formylpyrazoles and 3-hydroxyoxindoles in good to satisfactory overall yields (up to 91%) with excellent dr (all cases >20:1 dr) and high ee values (up to 99%).

Enantioselective Synthesis of Bispiro[indanedione-oxindole-cyclopropane]s through Organocatalytic [2+1] Cycloaddition.

A series of compounds featuring a novel bispiro[indanedione-oxindole-cyclopropane] moiety have been synthesized through a squaramide-catalyzed [2+1] cycloaddition reaction. The tandem Michael-alkylation reaction of 2-arylidene-1,3-indanediones with 3-bromooxindoles furnished the cycloadducts in high yields with excellent diastereo- and enantioselectivities. The ammonium ylide in the catalytic process, as a key intermediate, was revealed by the high-resolution mass spectrometry study.

Disproportionate Coupling Reaction of Sodium Sulfinates Mediated by BF·OEt: An Approach to Symmetrical/Unsymmetrical Thiosulfonates.

The BF·OEt-mediated disproportionate coupling reaction of sodium sulfinates was found for the first time. In this reaction, various S-S(O) bonds can be formed, efficiently giving thiosulfonates in moderate to excellent yields. As a convenient protocol for the synthesis of symmetrical and unsymmetrical thiosulfonates, its reaction mechanism involves the formation of a thiyl radical and sulfonyl radical via a sulfinyl radical disproportionation.

Ru-indoloquinoline complex as a selective and effective human telomeric G-quadruplex binder.

Indoloquinoline and its derivatives have been reported to be a kind of efficient G-quadruplex binder and have been found to interact preferentially to intramolecular G-quadruplex and inhibit telomerase activity in human K562 cells and SW620 cells. In contrast to indoloquinoline derivatives, much less is known about the metal complex based on indoloquinoline or its derivative. In this report, we studied the interaction of ruthenium complex [Ru(bpy)2(itatp)]2+ containing indoloquinoline moiety with human telomeric G-quadruplex DNA (Telo22) and c-myc G-quadruplex DNA (Pu27) by UV-visible (UV-Vis), fluorescence spectroscopy, fluorescent intercalator displacement (FID), thermal denaturation studies and CD spectroscopy.

Interactions of ruthenium complexes containing indoloquinoline moiety with human telomeric G-quadruplex DNA.

G-quadruplex structures are attractive targets for the development of anticancer drugs, as their formation in human telomere could impair telomerase activity, thus inducing apoptosis in cancer cells. Vast majority of G-quadruplex binding molecules have been designed and synthesized. Ruthenium complexes have also been reported to induction or stabilization of G-quadruplex structure of human telomeric sequence, whereas most of them generally promote the formation of antiparallel or hybrid-type G-quadruplex structure.

Synthesis, visible light photocleavage, antiproliferative and cellular uptake properties of ruthenium complex [Ru(phen)2(mitatp)]2+.

A new ruthenium complex [Ru(phen)(2)(mitatp)](2+) (phen = 1,10-phenanthroline, mitatp = 5-methoxy-isatino[1,2-b]-1,4,8,9-tetraazatriphenylene) has been synthesized and characterized. The interaction of the complex with DNA has been studied and the results indicate that [Ru(phen)(2)(mitatp)](2+) could efficiently photocleave pBR322 DNA under irradiation at visible light and the singlet oxygen (1)O(2) was proved to be reactive species in the photocleavage process. The cytotoxicity has also been evaluated by MTT method, and [Ru(phen)(2)(mitatp)](2+) shows prominent anticancer activity against various cancer cells.

A pheromone-rate-based analysis on the convergence time of ACO algorithm.

Ant colony optimization (ACO) has widely been applied to solve combinatorial optimization problems in recent years. There are few studies, however, on its convergence time, which reflects how many iteration times ACO algorithms spend in converging to the optimal solution. Based on the absorbing Markov chain model, we analyze the ACO convergence time in this paper.