Curtius Rearrangement

3 Key excerpts on "Curtius Rearrangement"

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  eBook - PDF

  Name Reactions for Homologation, Part 2

  • Jie Jack Li(Author)
  • 2009(Publication Date)
  • Wiley

    (Publisher)

  Because of the vast literature on the Curtius Rearrangement, including many excellent review articles,’-12 this chapter, while describing some classic examples, will emphasize recent applications of the reaction, including its application in synthetically challenging, highly functionalized molecular frameworks. 1.1.4.2 Historical Perspective During the 189Os, Thomas Curtius studied the preparation and reactions of acyl azides. For example, treatment of benzoylhydrazine (1) with nitrous acid provided benzoyl azide,13 which Curtius represented as 2, consistent Chapter 1. Rearrangements 137 with the then-accepted cyclic azido structure. In the presence of water, heating benzoyl azide liberated molecular nitrogen and carbon dioxide and gave an organic product C13H12N20 that Curtius showed was dipheny1~rea.l~ This established the carbon-to-nitrogen change in connectivity of the original acyl substituent during the reaction. The same urea product resulted when Curtius heated benzoyl azide in the presence of aniline. 1 1 0 0 1 1 0 1 2 N 3 (2 equiv) HONO PhAN

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  Organic Reaction Mechanisms 1975

  An annual survey covering the literature dated December 1974 through November 1975

  • A. R. Butler, M. J. Perkins, A. R. Butler, M. J. Perkins(Authors)
  • 2008(Publication Date)
  • Wiley-Interscience

    (Publisher)

  The Curtius and Lossen rearrangements have been used to prepare N-phosphorylated alkylureas and urethanes,MO benzimid- azolones, phthalaz-4-ones and benzoxazoles.841 An unusual reorganization leading to PhNHCONRR’occurs when N-(phenylsulphiny1oxy)benzamide is treated with RR’NH, PhNCO being presumably involved as an intermediatemu* Substituted benzhydryl azides react with nitrosonium tetrafluoroborate in anhydrous acetonitrile to give benzaldehydesand benzophenonesin addition to products emane;ting from the benzhydryl cation.* A detailed examination of aubstituent effects ( p = -0.64) and a comparison of the migratory aptitudes of substituted benzhydryl azides indicate that the aldehydic products are formed from azide in a reaction with benzhydryl cation formally analogous to the Curtius Rearrangement, rather than by phenyl-migration to N. The substituted bemophenones are formed by hydride-migration to nitrogen, a processthat has not been observed in rearrangement of benzhydryl azides in protic acids. The rates of thermal rearrangement of N-benzoyl-N-methyl-O-thiocarbamoyl- hydroxylamines to S-carbamoyl N-methylbenzothiohydroxamates and the correspond- ing N-methylbenzamideare not appreciably influenced either by solvent polarity or by para-substitution in the benzene ring.w The data are most readily interpreted in terms of a concerted or a free-radical-pair pathway, although the extent of the relative contribution of radical-pair and sigmatropic [1,3]-ahift in these rearrangements, is not likely to be resolved simply. The results of the lead tetra-acetate-induced Stieglitz rearrangement with various para-substituted triarylmethylamines have been pre- sented;=s a pathway involving a concerted migration of the aryl group with the de- parture of the lead acetate or its triacetoxyplumbate anion (see Scheme 13) seems most consistent with the results, although these do not completely preclude a nitrenium ion rationale.

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  Organic Reaction Mechanisms 2017

  An annual survey covering the literature dated January to December 2017

  • A. C. Knipe, Mark G. Moloney, A. C. Knipe, Mark G. Moloney(Authors)
  • 2020(Publication Date)
  • Wiley

    (Publisher)

  The Schmidt reaction, an acid-catalysed analogue of the Curtius reaction, has been explored by computational methods, and the concerted pathway is favoured. 106 R OH O azide-free alternative O O N R O O hv copper catalyst − CO 2 N R Figure 76 O BzO OAc BzO OBz + N N R X NH 2 R = NH 2 Cl O BzO N BzO OBz N R X NH Dimroth rearrangement O BzO NH BzO OBz N N NH 2 X Figure 77 558 Organic Reaction Mechanisms 2017 Dimroth Rearrangement Dimroth rearrangement in the ribosylation of 4-aminopyrimidines has been reported 107 (Figure 77). Fischer Indole An acid-catalysed Fischer indolization is a central step in the synthesis of an androgen recep-tor modulator, ( S )-(7-cyano-4-(pyridin-2-ylmethyl)-1,2,3,4-tetrahydrocyclopenta[ b ]indol-2-yl) carbamic acid isopropyl ester, LY2452473, used for a promising treatment of side effects of prostate cancer therapies. 108 Friedel–Crafts Friedel–Crafts monoacylation and diacylation of fluoranthene have been reported. 109 Heyns Rearrangement The regiochemistry of Heyns rearrangement in fructosazone formation has been reported. 110 Lossen Rearrangement The direct conversion of a hydroxamic acid to an amine in a single step is reported in the syn-thesis of HIV drug candidate BMS-955176 111 (Figure 78). Meyer–Schuster The cooperatively catalysed Meyer–Schuster rearrangement/Tsuji–Trost allylic substitution reactions of propargylic alcohols and allylic carbonates, with vanadium and palladium catalysts, have been examined using computational methods. 112 Mislow–Evans A review of the Mislow–Evans rearrangement has established the [2,3]-sigmatropic nature of the reaction and described its synthetic applications, including extensions at the forefront of current-day challenges in organic synthesis. 113 Morita–Baylis–Hillman 6 𝜋 -Electrocyclization of conjugated trienes derived in situ from the Morita–Baylis–Hillman carbonates of N -methylisatins afforded dispirocyclohexadiene bisoxindoles 114 (Figure 79).

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