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Jetze J. Tepe - One of the best experts on this subject based on the ideXlab platform.
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One-pot Friedel-Crafts/Robinson-Gabriel synthesis of Oxazoles using oxazolone templates.
The Journal of organic chemistry, 2005Co-Authors: Manasi Keni, Jetze J. TepeAbstract:We report herein a one-pot synthesis of 2,4,5-trisubstituted Oxazoles via a Friedel−Crafts/Robinson−Gabriel synthesis using a general oxazolone template. Treatment of the oxazolone template with a range of aromatic nucleophiles provided the highly substituted Oxazoles in good yields.
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one pot friedel crafts robinson gabriel synthesis of Oxazoles using oxazolone templates
Journal of Organic Chemistry, 2005Co-Authors: Manasi Keni, Jetze J. TepeAbstract:We report herein a one-pot synthesis of 2,4,5-trisubstituted Oxazoles via a Friedel−Crafts/Robinson−Gabriel synthesis using a general oxazolone template. Treatment of the oxazolone template with a range of aromatic nucleophiles provided the highly substituted Oxazoles in good yields.
Manasi Keni - One of the best experts on this subject based on the ideXlab platform.
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One-pot Friedel-Crafts/Robinson-Gabriel synthesis of Oxazoles using oxazolone templates.
The Journal of organic chemistry, 2005Co-Authors: Manasi Keni, Jetze J. TepeAbstract:We report herein a one-pot synthesis of 2,4,5-trisubstituted Oxazoles via a Friedel−Crafts/Robinson−Gabriel synthesis using a general oxazolone template. Treatment of the oxazolone template with a range of aromatic nucleophiles provided the highly substituted Oxazoles in good yields.
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one pot friedel crafts robinson gabriel synthesis of Oxazoles using oxazolone templates
Journal of Organic Chemistry, 2005Co-Authors: Manasi Keni, Jetze J. TepeAbstract:We report herein a one-pot synthesis of 2,4,5-trisubstituted Oxazoles via a Friedel−Crafts/Robinson−Gabriel synthesis using a general oxazolone template. Treatment of the oxazolone template with a range of aromatic nucleophiles provided the highly substituted Oxazoles in good yields.
Andreas Pfaltz - One of the best experts on this subject based on the ideXlab platform.
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C2‐Symmetric 4,4′,5,5′‐Tetrahydrobi(Oxazoles) and 4,4′,5,5′‐Tetrahydro‐2,2′‐methylenebis[Oxazoles] as Chiral Ligands for Enantioselective Catalysis Preliminary Communication
Helvetica Chimica Acta, 1991Co-Authors: Dieter Müller, Gisela Umbricht, Beat Weber, Andreas PfaltzAbstract:The synthesis of a series of enantiomerically pure, C2-symmetric 4,4′,5,5′-tetrahydro-2,2′-methylenebis[Oxazoles] and 4,4′,5,5′-tetrahydro-2,2′-bi(Oxazoles) is reported. Copper complexes with anionic tetrahydromethylenebis[oxazole] ligands are efficient catalysts for the enantioselective cyclopropane formation from olefins and diazo compounds (up to 96% ee in the reaction of styrene with menthyl diazoacetate). Tetrahydrobi(oxazole)iridium(I) complexes were found to catalyze transfer hydrogenations of aryl alkyl ketones with i-PrOH (up to 91% ee). Tetrahydrobi(oxazole)palladium complexes can be used as enantioselective catalysts for allylic nucleophilic substitution (up to 77% ee in the reaction of PhCHCHCH(OAc)Ph with NaHC(COOMe)2).
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c2 symmetric 4 4 5 5 tetrahydrobi Oxazoles and 4 4 5 5 tetrahydro 2 2 methylenebis Oxazoles as chiral ligands for enantioselective catalysis preliminary communication
Helvetica Chimica Acta, 1991Co-Authors: Dieter Müller, Gisela Umbricht, Beat Weber, Andreas PfaltzAbstract:The synthesis of a series of enantiomerically pure, C2-symmetric 4,4′,5,5′-tetrahydro-2,2′-methylenebis[Oxazoles] and 4,4′,5,5′-tetrahydro-2,2′-bi(Oxazoles) is reported. Copper complexes with anionic tetrahydromethylenebis[oxazole] ligands are efficient catalysts for the enantioselective cyclopropane formation from olefins and diazo compounds (up to 96% ee in the reaction of styrene with menthyl diazoacetate). Tetrahydrobi(oxazole)iridium(I) complexes were found to catalyze transfer hydrogenations of aryl alkyl ketones with i-PrOH (up to 91% ee). Tetrahydrobi(oxazole)palladium complexes can be used as enantioselective catalysts for allylic nucleophilic substitution (up to 77% ee in the reaction of PhCHCHCH(OAc)Ph with NaHC(COOMe)2).
Paul Knochel - One of the best experts on this subject based on the ideXlab platform.
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Regioselective functionalization of the oxazole scaffold using TMP-bases of Mg and Zn.
Organic letters, 2013Co-Authors: Diana Haas, Marc Mosrin, Paul KnochelAbstract:A general method for the synthesis of 2,4,5-trisubstituted Oxazoles has been developed. Starting from commercially available oxazole, successive metalations using TMPMgCl·LiCl or TMPZnCl·LiCl led to the corresponding magnesiated or zincated species which were stable toward ring fragmentation. Furthermore, they readily reacted with various electrophiles, such as aryl and allylic halides, acid chlorides, TMSCl, and TMS-CN, providing highly functionalized Oxazoles.
Christopher J. Moody - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of functionalised Oxazoles and bis-Oxazoles1
Journal of the Chemical Society Perkin Transactions 1, 1998Co-Authors: Mark C. Bagley, Richard T. Buck, S. Lucy Hind, Christopher J. MoodyAbstract:A new method for the synthesis of Oxazoles, and in particular chiral non-racemic Oxazoles derived from amino acids, has been developed. Thus, rhodium(II) catalysed reaction of diazocarbonyl compounds 6 and 11 in the presence of amides 8 and 10 results in regioselective insertion of the carbenoid into the amide N–H bond with formation of the β-carbonyl amides 9 and 12. Cyclodehydration of amides 9 and 12 using triphenylphosphine–iodine–triethylamine gives functionalised Oxazoles 7 and 13. The Oxazoles 13c and 13f were converted into the bis-Oxazoles 17a and 17b by a second rhodium(II) catalysed regioselective N–H insertion reaction on the amides 15, followed by cyclodehydration.
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Chapter 1 The synthesis of Oxazoles from diazocarbonyl compounds
Progress in Heterocyclic Chemistry, 1997Co-Authors: Christopher J. Moody, Kevin J. DoyleAbstract:Publisher Summary This chapter presents a study on the synthesis of Oxazoles from diazocarbonyl compounds. The chapter presents a work, summarized in the classic treatise in 1949, is the foundation of modern oxazole chemistry. The subsequent discovery during the 1950's by Kondrat’eva that Oxazoles can function as azadienes in the Diels–Alder reaction, and by Huisgen that mesoionic Oxazoles participate in 1,3-dipolar cycloaddition reactions prompted further research into the ring system. Recently the oxazole ring system has been found in an ever increasing range of natural products, many of them “peptide alkaloids” in which the heterocyclic ring is most likely formed by a modification of a serine or threonine containing peptide. There are several methods available for the synthesis of Oxazoles; this chapter focuses on just one route, which has been used extensively in a laboratory—namely, that involving the reaction of diazocarbonyl compounds with nitriles. Oxazole formation can be envisaged as proceeding by the following three possible pathways: (1) 1,3-dipolar cycloaddition of a free ketocarbene to the nitrile (Path A); (2) the formation and subsequent 1,5-cyclisation of a nitrile ylide (Path B); or (3) the formation and subsequent rearrangement of a 2- acyl-2H-azirine (Path C). The role of Lewis acids in the formation of Oxazoles from diazocarbonyl compounds and nitriles has been discussed. The chapter also discusses transition-metal catalyzed reactions, including copper, tungsten, palladium, and rhodium.
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The rhodium carbenoid route to Oxazoles. Synthesis of 4-functionalised Oxazoles; Three step preparation of a bis-oxazole
Tetrahedron, 1994Co-Authors: Kevin J. Doyle, Christopher J. MoodyAbstract:Abstract Oxazole-4-sulfones, -phosphonates, and -nitriles are prepared by rhodium(II) catalysed addition of nitriles to the corresponding diazo compound. The effect of the ligand on rhodium was briefly investigated, with rhodium(II) trifluoroacetamide generally proving the most effective catalyst. The 4-cyanooxazole 9 is readily converted into the bis-Oxazoles 10–12.
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Diazo-sulfones and -nitriles in oxazole synthesis; three step preparation of a bis-oxazole
Tetrahedron Letters, 1992Co-Authors: Kevin J. Doyle, Christopher J. MoodyAbstract:Abstract Oxazole-4-sulfones and -nitriles are prepared by rhodium(II) catalysed addition of nitriles to the corresponding diazo compound: the 4-cyanooxazole 3 is readily converted into the bis-Oxazoles 4 and 5 .