Oxazoles

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Jetze J. Tepe - One of the best experts on this subject based on the ideXlab platform.

Manasi Keni - One of the best experts on this subject based on the ideXlab platform.

Andreas Pfaltz - One of the best experts on this subject based on the ideXlab platform.

Paul Knochel - One of the best experts on this subject based on the ideXlab platform.

Christopher J. Moody - One of the best experts on this subject based on the ideXlab platform.

  • Synthesis of functionalised Oxazoles and bis-Oxazoles1
    Journal of the Chemical Society Perkin Transactions 1, 1998
    Co-Authors: Mark C. Bagley, Richard T. Buck, S. Lucy Hind, Christopher J. Moody
    Abstract:

    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.

  • Chapter 1 The synthesis of Oxazoles from diazocarbonyl compounds
    Progress in Heterocyclic Chemistry, 1997
    Co-Authors: Christopher J. Moody, Kevin J. Doyle
    Abstract:

    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.

  • The rhodium carbenoid route to Oxazoles. Synthesis of 4-functionalised Oxazoles; Three step preparation of a bis-oxazole
    Tetrahedron, 1994
    Co-Authors: Kevin J. Doyle, Christopher J. Moody
    Abstract:

    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.

  • Diazo-sulfones and -nitriles in oxazole synthesis; three step preparation of a bis-oxazole
    Tetrahedron Letters, 1992
    Co-Authors: Kevin J. Doyle, Christopher J. Moody
    Abstract:

    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 .