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Wang Jianbo - One of the best experts on this subject based on the ideXlab platform.

  • C-H Bond Functionalization of Benzoxazoles with Chromium(0) Fischer Carbene Complexes
    ORGANOMETALLICS, 2016
    Co-Authors: Hu Fangdong, Yang Jinghui, Xia Ying, Ma Chen, Xia Haiping, Zhang Yan, Wang Jianbo
    Abstract:

    An efficient C-H bond functionalization of Benzoxazoles with chromium(0) Fischer carbene complexes under catalyst-free conditions has been developed. A series of Benzoxazoles and chromium(0) carbene complexes are compatible with the reaction. This transformation provides an alternative way for C-H bond alkylation of Benzoxazoles. In the reaction mechanism the elimination of the Cr(CO)(5) fragment seems more favored than the elimination of an alkoxy group, which is in sharp contrast to the previous reports on the reaction of organolithium reagents with chromium(0) Fischer carbene complexes.National Basic Research Program of China (973 Program) [2012CB821600]; Natural Science Foundation of China [21472004, 21332002]SCI(E)EIARTICLEwangjb@pku.edu.cn101409-14143

Edgars Suna - One of the best experts on this subject based on the ideXlab platform.

  • Synthesis of Benzoxazoles Using Electrochemically Generated Hypervalent Iodine
    Journal of Organic Chemistry, 2017
    Co-Authors: Olesja Koleda, Edgars Suna, Timo Broese, Jan Noetzel, Michael Roemelt, R Francke
    Abstract:

    The indirect (“ex-cell”) electrochemical synthesis of Benzoxazoles from imines using a redox mediator based on the iodine(I)/iodine(III) redox couple is reported. Tethering the redox-active iodophenyl subunit to a tetra-alkylammonium moiety allowed for anodic oxidation to be performed without supporting electrolyte. The mediator salt can be easily recovered and reused. Our “ex-cell” approach toward the electrosynthesis of Benzoxazoles is compatible with a range of redox-sensitive functional groups. An unprecedented concerted reductive elimination mechanism for benzoxazole formation is proposed on the basis of control experiments and DFT calculations.

  • Synthesis of Benzoxazoles Using Electrochemically Generated Hypervalent Iodine
    2017
    Co-Authors: Olesja Koleda, Edgars Suna, Timo Broese, Jan Noetzel, Michael Roemelt, R Francke
    Abstract:

    The indirect (“ex-cell”) electrochemical synthesis of Benzoxazoles from imines using a redox mediator based on the iodine­(I)/iodine­(III) redox couple is reported. Tethering the redox-active iodophenyl subunit to a tetra-alkylammonium moiety allowed for anodic oxidation to be performed without supporting electrolyte. The mediator salt can be easily recovered and reused. Our “ex-cell” approach toward the electrosynthesis of Benzoxazoles is compatible with a range of redox-sensitive functional groups. An unprecedented concerted reductive elimination mechanism for benzoxazole formation is proposed on the basis of control experiments and DFT calculations

  • parallel synthesis of Benzoxazoles via microwave assisted dielectric heating
    Tetrahedron Letters, 2003
    Co-Authors: Richard S. Pottorf, Naresh Chadha, Martins Katkevics, Vita Ozola, Edgars Suna, Hadi Ghane, Tor Regberg, Mark R Player
    Abstract:

    A facile route to Benzoxazoles has been developed using microwave-assisted dielectric heating. The ease of synthesis and workup allowed the parallel synthesis of a 48-membered library of Benzoxazoles quickly and efficiently.

R Francke - One of the best experts on this subject based on the ideXlab platform.

  • Synthesis of Benzoxazoles Using Electrochemically Generated Hypervalent Iodine
    Journal of Organic Chemistry, 2017
    Co-Authors: Olesja Koleda, Edgars Suna, Timo Broese, Jan Noetzel, Michael Roemelt, R Francke
    Abstract:

    The indirect (“ex-cell”) electrochemical synthesis of Benzoxazoles from imines using a redox mediator based on the iodine(I)/iodine(III) redox couple is reported. Tethering the redox-active iodophenyl subunit to a tetra-alkylammonium moiety allowed for anodic oxidation to be performed without supporting electrolyte. The mediator salt can be easily recovered and reused. Our “ex-cell” approach toward the electrosynthesis of Benzoxazoles is compatible with a range of redox-sensitive functional groups. An unprecedented concerted reductive elimination mechanism for benzoxazole formation is proposed on the basis of control experiments and DFT calculations.

  • Synthesis of Benzoxazoles Using Electrochemically Generated Hypervalent Iodine
    2017
    Co-Authors: Olesja Koleda, Edgars Suna, Timo Broese, Jan Noetzel, Michael Roemelt, R Francke
    Abstract:

    The indirect (“ex-cell”) electrochemical synthesis of Benzoxazoles from imines using a redox mediator based on the iodine­(I)/iodine­(III) redox couple is reported. Tethering the redox-active iodophenyl subunit to a tetra-alkylammonium moiety allowed for anodic oxidation to be performed without supporting electrolyte. The mediator salt can be easily recovered and reused. Our “ex-cell” approach toward the electrosynthesis of Benzoxazoles is compatible with a range of redox-sensitive functional groups. An unprecedented concerted reductive elimination mechanism for benzoxazole formation is proposed on the basis of control experiments and DFT calculations

Asit K Chakraborti - One of the best experts on this subject based on the ideXlab platform.

  • 2 2 arylphenyl benzoxazole as a novel anti inflammatory scaffold synthesis and biological evaluation
    ACS Medicinal Chemistry Letters, 2014
    Co-Authors: Kapileswar Seth, Sanjeev K Garg, Priyank Purohit, Vachan S Meena, Rohit Goyal, Uttam Chand Banerjee, Raj Kumar, Asit K Chakraborti
    Abstract:

    The 2-(2-arylphenyl)benzoxazole moiety has been found to be a new and selective ligand for the enzyme cyclooxygenase-2 (COX-2). The 2-(2-arylphenyl)Benzoxazoles 3a–m have been synthesized by Suzuki reaction of 2-(2-bromophenyl)benzoxazole. Further synthetic manipulation of 3f and 3i led to 3o and 3n, respectively. The compounds 3g, 3n, and 3o selectively inhibited COX-2 with selectivity index of 3n much better than that of the COX-2 selective NSAID celecoxib. The in vivo anti-inflammatory potency of 3g and 3n is comparable to that of celecoxib and the nonselective NSAID diclofenac at two different doses, and 3o showed better potency compared to these clinically used NSAIDs.

  • One-Pot Synthesis of 2-Substituted Benzoxazoles Directly from Carboxylic Acids
    Australian Journal of Chemistry, 2008
    Co-Authors: Dinesh Kumar, Santosh Rudrawar, Asit K Chakraborti
    Abstract:

    Methanesulfonic acid has been found to be a highly effective catalyst for a convenient and one-pot synthesis of 2-substituted Benzoxazoles by the reaction of 2-aminophenol with acid chlorides, generated in situ from carboxylic acids. Aryl, heteroaryl, and arylalkyl carboxylic acids provided excellent yields of the corresponding Benzoxazoles. The reaction conditions were compatible with various substituents such as chloro, bromo, nitro, methoxy, cyclopentyloxy, phenoxy, thiophenoxy, and conjugated double bonds. Benzoxazole formation was found to be general with respect to substituted 2-aminophenols.

Lon J. Mathias - One of the best experts on this subject based on the ideXlab platform.

  • Intermediates and monomers for vapor phase deposition and polyBenzoxazoles
    Designed Monomers and Polymers, 2012
    Co-Authors: Tina L. Grubb, Lon J. Mathias
    Abstract:

    New multifunctionalized aliphatic and aromatic Benzoxazoles have been synthesized as potential intermediates for benzoxazole cyclic dimers and soluble polymeric precursors to fully conjugated vinylene phenylene polymer structures. Aliphatic Benzoxazoles were found to undergo hydrolysis under the normal basic conditions required for carbon-carbon coupling reactions to form cyclic dimers. In attempts to form aromatic benzoxazole cyclic dimers, polymerization occurred, demonstrating facile reaction. Although benzoxazole cyclic dimers were never isolated for vapor phase deposition-polymerization, the new functionalized Benzoxazoles synthesized here, namely the dihalomethyl and monohalomethyl derivatives, are being investigated as potential vapor phase deposition-polymerization monomers.

  • Vapor phase deposition of polyBenzoxazoles
    Journal of Polymer Science Part A, 1998
    Co-Authors: Lon J. Mathias, Tina L. Grubb, Gordon L. Tullos
    Abstract:

    Vapor phase deposition was carried out on multifunctional aliphatic and aromatic Benzoxazoles to yield powdered samples of poly(dimethyleneBenzoxazoles). Representative aliphatic and aromatic poly(dimethyleneBenzoxazoles) were also synthesized through solution methods using 4-amino-3-hydroxyhydrocinnamic acid and 2-(4-(bromomethyl)phenyl)-6-(bromomethyl)benzoxazole, respectively, as monomers. Both aromatic and aliphatic polyBenzoxazoles containing CH2CH2 units in the polymer backbone displayed catastrophic weight loss over a very narrow temperature range. This is in contrast with other polyBenzoxazoles which show a gradual weight loss over 500–1000°C. Vapor phase deposition carried out under vacuum on the polymers gave similar polymers in the collection zone suggesting the catastrophic weight loss is attributed to thermal depolymerization of the polymer through a diradical intermediate similar to the thermolysis and polymerization of [2.2]paracyclophane. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1317–1328, 1998