Inhaltszusammenfassung

Experimentally determined barriers to O-acyl group topomerization in mixed anhydrides composed of beta-disubstituted carboxylic acids and cyclic thiohydroxamic acid N-hydroxy-4-methylthiazole-2(3H)-thione were located in the range of Delta G double dagger(320)=68 +/- 8 kJ mol(-1) (DNMR). According to modeling studies, the underlying exchange process is proposed to occur via rotation about the N,O bond for torsional movement of the O-acyl group past the heterocyclic 4-methyl substituent. The e...Experimentally determined barriers to O-acyl group topomerization in mixed anhydrides composed of beta-disubstituted carboxylic acids and cyclic thiohydroxamic acid N-hydroxy-4-methylthiazole-2(3H)-thione were located in the range of Delta G double dagger(320)=68 +/- 8 kJ mol(-1) (DNMR). According to modeling studies, the underlying exchange process is proposed to occur via rotation about the N,O bond for torsional movement of the O-acyl group past the heterocyclic 4-methyl substituent. The energetically lowest pathway for passing the O-acyl entity by the thione sulfur, is predicted to occur via sequential rocking about the C-sP2,O single bond in combination with an interlaced twist about the N,O axis. (C) 2009 Elsevier Ltd. All rights reserved. » weiterlesen» einklappen

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