Search results for "combinatorial"

Achieving Unbounded Resolution inFinitePlayer Goore Games Using Stochastic Automata, and Its Applications

2012

Abstract This article concerns the sequential solution to a distributed stochastic optimization problem using learning automata and the Goore game (also referred to as the Gur game in the related literature). The amazing thing about our solution is that, unlike traditional methods, which need N automata (where N determines the degree of accuracy), in this article, we show that we can obtain arbitrary accuracy by recursively using only three automata. To be more specific, the Goore game (GG) introduced in Tsetlin (1973) has the fascinating property that it can be resolved in a completely distributed manner with no inter-communication between the players. The game has recently found applicati…

Synthesis of Pyrrolidin-2-ones and of Staurosporine Aglycon (K-252c) by Intermolecular Michael Reaction

1999

Indolo[2,3-a]pyrrolo[3,4-c]carbazoles were isolated from nature, e.g., from low plants, especially fungi, as structurally rare natural substances. Responsible for naming and also the most important representative of this type is staurosporine (1), isolated from Streptomyces staurosporeus, and its aglycon (2), also known as staurosporinone or K-252c. 3,4-Disubstituted pyrrolidin-2-ones, a group of compounds with many interesting biological properties are related to staurosporinone. The most important property is the inhibition of protein kinase C (PKC), so that this antiproliferative agent can interfere with the cell cycle. The synthetic strategy, developed by us, allows the synthesis of pyr…

tBuLi-Mediated One-Pot Direct Highly Selective Cross-Coupling of Two Distinct Aryl Bromides.

2015

A Pd-catalyzed direct cross-coupling of two distinct aryl bromides mediated by tBuLi is described. The use of [Pd-PEPPSI-IPr] or [Pd-PEPPSI-IPent] as catalyst allows for the efficient one-pot synthesis of unsymmetrical biaryls at room temperature. The key for this selective cross-coupling is the use of an ortho-substituted bromide that undergoes lithium-halogen exchange preferentially.

Antiproliferative agents that interfere with the cell cycle at the G(1)-->S transition: further development and characterization of a small library o…

2008

In this continuation of our research on derivatives containing the stilbene privileged structure or that are derived from it, we report the results of further studies carried out on the previously initiated collection of compounds. We used a parallel synthetic approach to rapidly obtain small sets of compounds and started the annotation of the library in progress by calculating some physicochemical properties to be eventually correlated with biological activities. A pharmacophore for the antiproliferative activity was also built to summarize the features of the library. We evaluated the antiproliferative and pro-apoptotic activities of all compounds as well as the cell-cycle effects of some…

Topologically Novel Multiple Rotaxanes and Catenanes Based on Tetraurea Calix[4]arenes

2006

Calix[4]arenes bearing at their wide rim four urea residues easily form hydrogen bonded dimeric capsules. This has been used to preorganise alkenyl functions attached to these urea groups for their controlled connection via metathesis reaction. Multimacrocyclic tetraurea derivatives are thus obtained in excellent yields via heterodimers which are formed exclusively with tetratosylurea derivatives. Heterodimerisation of such bis- and tetraloop tetraureas leads analogously to multicatenanes, or to rotaxanes by stoppering. Huge macrocycles are detached from tetraloop derivatives by cleavage of the urea function.

A monophosphoryl copillar[5]arene: synthesis and host–guest complexation with alkanols

2013

A monophosphoryl copillar[5]arene 1 was prepared. The introduction of the phosphoryl group remarkably promoted the binding affinity of 1 with alkanols and alkanediols in comparison with 1,4-dimethoxypillar[5]arene. Thus 1 can form a stable 1 : 1 host–guest complex with alkanols in CDCl3.

ChemInform Abstract: Synthesis, Structure Determination by NMR, and Inhibitory Activity Against Mouse Lymphoma Cells (L5178-y) of Dipyrimidothiophene…

2010

Triazolopyridines. Part 25: Synthesis of new chiral ligands from [1,2,3]triazolo[1,5-a]pyridines

2007

The synthesis of new chiral triazolopyridine ligands possessing fluorescent properties is described. The triazolo ring opening was studied in order to obtain new chiral 2,6-disubstituted pyridines. A preliminary coordination assay with Zn(II) is also presented.

Palladium-catalyzed Suzuki-Miyaura reaction involving a secondary sp3 carbon: studies of stereochemistry and scope of the reaction.

2007

Palladium-catalyzed C--C bond formation involving secondary sp3-hybridized carbon is described. These reactions occur with secondary 1-bromoethyl arylsulfoxides and different arylboronic acids, to produce the corresponding arylated sulfoxides in moderate to high yields and with complete stereospecificity. Despite the presence of beta hydrogens in the substrate, the competitive beta-hydride elimination is not a significant side reaction when coordinating solvents are used. The reported cross-coupling involves secondary C(sp3)--C(sp2) bond formation: this is the first time that a mechanistic study has been carried out with such substrates. The reaction proceeds with inversion of configuration…

Annelated pyrrolo-pyrimidines from amino-cyanopyrroles and BMMAs as leads for new DNA-interactive ring systems.

2005

The efficient one-pot synthesis of several new tricyclic systems of type 1 and 2, obtained from the reaction of substituted 2-amino-3-cyanopyrroles and 3-amino-4-cyanopyrroles with BMMAs, is reported. The duration and yields of the reaction strongly depend on the reactivity of the starting pyrrole and on the size of the ring to be formed. Mechanist features of the reaction were investigated and proposed by studying also the reactivity of a 3-aminopyrrole-2,4-dicyano substituted. The method reported represents the first example of the use of BMMA reagents in combination with pyrrole derivatives and allows an easy and versatile entry to a large number of hitherto unknown pyrrolo-pyrimidines f…