Benzo[7,8]indolizinoquinoline scaffolds based on Mg(ClO4)2-promoted regiospecific imide reduction and π-cyclization of N-acyliminium species. Analogues of the topo-1 poison rosettacin and 22-hydroxyacuminatine alkaloids
Abstract : A general five-step synthesis of a short library of benzo[7,8]indolizinoquinolinine analogues of the topoisomerase-1 (topo-1) poison rosettacin and 22-hydroxyacuminatine alkaloids from DMAD and ortho-ketoanilines is reported. This consists on successively, the tandem aza-Michael addition/cyclodehydration, the hydrolysis of the resulting diesters into corresponding o-dicarboxylic acids, and the tandem intermolecular amidation/cyclodehydration into N-substituted imides. The regioselective reduction of one imide carbonyl into corresponding α-hydroxy lactams promoted by a Lewis acid Mg(ClO4)2 was followed ultimately with TFA-promoted π-cationic cyclization via stable N-acyliminiums species as an important key step.
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Abdulkareem Hamid, Abdelaziz Souizi, Ata Martin Lawson, Mohamed Othman, Alina Ghinet, et al.. Benzo[7,8]indolizinoquinoline scaffolds based on Mg(ClO4)2-promoted regiospecific imide reduction and π-cyclization of N-acyliminium species. Analogues of the topo-1 poison rosettacin and 22-hydroxyacuminatine alkaloids. Arabian Journal of Chemistry, Elsevier, 2019, 12 (5), pp.680-693. ⟨10.1016/j.arabjc.2018.03.009⟩. ⟨hal-02413296⟩