abstract
The synthesis of 1,5-benzodiazepines by the reaction of o-phenylenediamines (o-PDAs) with dehydroacetic acid DHAA [3-acetyl-4-hydroxy-6-methyl-2H-pyran-2-one] or conjugate analogues is largely reported in the literature, but still with uncontrolled stereochemistry. In this work, a comprehensive mechanistic study on the formation of some synthesized 1,5-benzodiazepine models following different organic routes is established based on liquid-state 2D NMR, single-crystal X-ray diffraction and theoretical calculations allowing the classification of two prototropic forms A (enaminopyran-2,4-dione) and B (imino-4-hydroxypyran-2-one). Evidences are presented to show that most of the reported 1,5-benzodiazepine structures arising from DHAA and derivatives preferentially adopt the (E)-enaminopyran-2,4-diones A. (C) 2014 Elsevier B.V. All rights reserved.
keywords
1,3,5-TRISUBSTITUTED PYRAZOLES; REGIOSELECTIVE SYNTHESIS; BENZODIAZEPINES; CHALCONES; AMINES
subject category
Chemistry
authors
Rabahi, A; Hamdi, SM; Rachedi, Y; Hamdi, M; Talhi, O; Almeida, FA; Silva, ASM; Fadila, B; Malika, H; Kamel, T
our authors
Flávia Aparecida de Almeida
Post-doc FellowshipGroups
acknowledgements
Thanks are due to the University of Aveiro, Fundacao para a Ciencia e a Tecnologia (FCT, Portugal), the European Union, QREN, FEDER, COMPETE, for funding the Organic Chemistry Research Unit (QOPNA) (project PEst-C/QUI/UI006212013), the Associated Laboratory CICECO (Pest C-CTM/LA0011/2013), and the Portuguese National NMR Network (RNRMN).