A THEORETICAL STUDY OF THE THERMAL CURTIUS REARRANGEMENT OF SOME CINNAMOYL AZIDES USING THE DFT APPROACH

Curtius rearrangement cinnamoyl azides DFT treatment one stage mechanism.

РАСЧЕТ ХАРАКТЕРИСТИК ОПТИЧЕСКОГО ПОГЛОЩЕНИЯ ФТОРИДОВ С УЧЕТОМ МНОГОЧАСТИЧНЫХ ЭФФЕКТОВ, FACILE SYNTHESIS AND CRYSTAL STRUCTURE OF 1,5-DIMETHYL-6-THIOXO-1,3,5-TRIAZINANE-2,4-DIONE, ...

Том 56, 4 UDC 541.6:547.12 A THEORETICAL STUDY OF THE THERMAL CURTIUS REARRANGEMENT OF SOME CINNAMOYL AZIDES USING THE DFT APPROACH Rafie H. Abu-Eittah1, Walid M.I. Hassan1, W. Zordok2 1Department of Chemistry, Faculty of Science, University of Cairo, Giza, Egypt E-mail: aboeittah@yahoo.com 2Department of Chemistry, Faculty of Science, University of Zagazig, Egypt Received September, 26, 2013 The thermal Curtius rearrangement of cinnamoyl azide, 1-azido-3-phenylprop-2-ene-1-one, and the reactions of some of its derivatives is studied theoretically using the DFT (B3LYP631G(d,p) approach. <...> The transition state was located and confirmed. <...> The Curtius rearrangement of the studied compounds is a one-stage, discrete reaction. <...> Thermal transformations of carbonyl azides into isocyanates (Curtius rearrangement) provide a source for rich synthetic chemistry [ 1—4]. <...> In the first (Scheme 1), the reaction proceeds in one stage with a synchronous formation of isocyanate and N2 evolution (a concerted mechanism). <...> The first stage is the N2 evolution with the formation of acyl nitrene and the second stage is the rearrangement of acyl nitrene into the product (Scheme 2). <...> Т. 56, 4 677 In the photochemical Curtius rearrangement the formation of acyl nitrene was proved [ 2 ]. <...> Thus, by analogy it was assumed that acyl nitrene participates in the thermal rearrangement of acyl azides. <...> The participation of acyl nitrene was found only in the thermal (and photochemical) decomposition of ethoxycarbonyl azide EtOC(O)N3 [ 6 ] and it was the only case of the thermal reaction in which nitrene was experimentally identified by a chemical method [ 7 ]. <...> The first systematic study of the thermal Curtius reaction of small azides provided by Rauk and Alewood [ 8 ] appointed out two degenerate states of formyl azide, one yielding carbonyl nitrene and another isocyanate. <...> Abu-Eittah et al. [ 9 ] using MP2/6-31G* calculations concluded that while the Curtius rearrangement of formyl azide proceeds in one stage with a simultaneous formation of isocyanate and N2 evolution (concerted mechanism), that of acetyl and benzoyl azides provides the twostage mechanism. <...> The PBE/TZ2P calculations performed by Zapalov and Tiger [ 11 ] suggest that the rearrangement of syn acyl azides is a one-stage process, in which the elimination of N2 occurs synchronously with the rearrangement of atoms and bonds to form isocyanates, whereas the rearrangement <...>

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