864825-98-9Relevant academic research and scientific papers
C-H bonds as ubiquitous functionality: A general approach to complex arylated imidazoles via regioselective sequential arylation of all three C-H bonds and regioselective n -alkylation enabled by SEM-group transposition
Joo, Jung Min,Toure, B. Barry,Sames, Dalibor
supporting information; experimental part, p. 4911 - 4920 (2010/10/21)
(Figure presented) Imidazoles are an important group of the azole family of heterocycles frequently found in pharmaceuticals, drug candidates, ligands for transition metal catalysts, and other molecular functional materials. Owing to their wide application in academia and industry, new methods and strategies for the generation of functionalized imidazole derivatives are in demand. We here describe a general and comprehensive approach for the synthesis of complex aryl imidazoles, where all three C-H bonds of the imidazole core can be arylated in a regioselective and sequential manner. We report new catalytic methods for selective C5- and C2-arylation of SEM-imidazoles and provide a mechanistic hypothesis for the observed positional selectivity based on electronic properties of C-H bonds and the heterocyclic ring. Importantly, aryl bromides and low-cost aryl chlorides can be used as arene donors under practical laboratory conditions. To circumvent the low reactivity of the C-4 position, we developed the SEM-switch that transfers the SEM-group from N-1 to N-3 nitrogen and thus enables preparation of 4-arylimidazoles and sequential C4-C5-arylation of the imidazole core. Furthermore, selective N3-alkylation followed by the SEM-group deprotection (trans-N-alkylation) allows for regioselective N-alkylation of complex imidazoles. The sequential C-arylation enabled by the SEM-switch allowed us to produce a variety of mono-, di-, and triarylimidazoles using diverse bromo- and chloroarenes. Using our approach, the synthesis of individual compounds or libraries of analogues can begin from either the parent imidazole or a substituted imidazole, providing rapid access to complex imidazole structures.
Efficient chemoenzymatic dynamic kinetic resolution of 1-heteroaryl ethanols
Vallin, Karl S. A.,Posaric, David Wensbo,Hamersak, Zdenko,Svensson, Mats A.,Minidis, Alexander B. E.
supporting information; experimental part, p. 9328 - 9336 (2010/03/24)
(Chemical Equation Presented) The scope and limitation of the combined ruthenium-lipase induced dynamic kinetic resolution (DKR) through O-acetylation of racemic heteroaromatic secondary alcohols, i.e., 1-heteroaryl substituted ethanols, was investigated. After initial screening of reaction conditions, Candida antarctica lipase B (Novozyme 435, N435) together with 4-chloro-phenylacetate as acetyl-donor for kinetic resolution (KR), in conjunction with the ruthenium-based Shvo catalyst for substrate racemization in toluene at 80°C, enabled DKR with high yields and stereoselectivity of various 1-heteroaryl ethanols, such as oxadiazoles, isoxazoles, 1H-pyrazole, or 1H-imidazole. In addition, DFT calculations based on a simplified catalyst complex model for the catalytic (de)hydrogenation step are in agreement with the previously reported outer sphere mechanism. These results support the further understanding of the mechanistic aspects behind the difference in reactivity of 1-heteroaryl substituted ethanols in comparison to reference substrates, as often referred to in the literature.
Catalytic C-H arylation of SEM-protected azoles with palladium complexes of NHCs and phosphines
Toure, B. Barry,Lane, Benjamin S.,Sames, Dalibor
, p. 1979 - 1982 (2007/10/03)
The synthesis and catalytic evaluation of palladium complexes containing imidazolyl carbene ligand of varying steric and electronic properties is reported. These complexes catalyze the efficient C-H arylation of SEM-protected azole heteroarenes and thus provide a good method for preparation of a wide range of arylated free (NH)-azoles including pyrroles, indoles, imidazoles, and imidazo[1,2-a]pyridines. The reaction is operationally simple; the complexes are insensitive to moisture.
Chemokine receptor binding heterocyclic compounds
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Page column 77, (2008/06/13)
This invention relates to a novel class of heterocyclic compounds that bind chemokine receptors, inhibiting the binding of their natural ligands thereby. These compounds result in protective effects against infection by HIV through binding to chemokine receptors, including CXCR4 and CCR5, thus inhibiting the subsequent binding by these chemokines. The present invention provides a compound of Formula I wherein, W is a nitrogen atom and Y is absent or, W is a carbon atom and Y═H; R1to R7may be the same or different and are independently selected from hydrogen or straight, branched or cyclic C1-6alkyl; R8is a substituted heterocyclic group or a substituted aromatic group Ar is an aromatic or heteroaromatic ring each optionally substituted at single or multiple, non-linking positions with electron-donating or withdrawing groups; n and n′ are independently, 0-2; X is a group of the formula: Wherein, Ring A is an optionally substituted, saturated or unsaturated 5 or 6-membered ring, and P is an optionally substituted carbon atom, an optionally substituted nitrogen atom, sulfur or oxygen atom. Ring B is an optionally substituted 5 to 7-membered ring. Ring A and Ring B in the above formula can be connected to the group W from any position via the group V, wherein V is a chemical bond, a (CH2)n″group (where n″=0-2) or a C═O group. Z is, (1) a hydrogen atom, (2) an optionally substituted C1-6alkyl group, (3) a C0-6alkyl group substituted with an optionally substituted aromatic or heterocyclic group, (4) an optionally substituted C0-6alkylamino or C3-7cycloalkylamino group, (5) an optionally substituted carbonyl group or sulfonyl. These compounds further include any pharmaceutically acceptable acid addition salts and metal complexes thereof and any stereoisomeric forms and mixtures of stereoisomeric forms thereof.
