Solvent-free solid acid-catalyzed electrophilic annelations: A new green approach for the synthesis of substituted five-membered N-heterocycles
An effective microwave-induced, solid acid-catalyzed, environmentally benign synthesis of substituted pyrroles, indoles and carbazoles under solvent-free conditions is described. The new synthetic methodology is based on the use of a considerably strong solid acid, K-10 montmorillonite. Both the cyclialkylation of amines and annelation of pyrroles and indoles have been completed within minutes and provided excellent (75-98%) yields with practically 100% selectivity.
Synthesis and evaluation of novel ellipticines as potential anti-cancer agents
Drugs that inhibit DNA topoisomerase I and DNA topoisomerase II have been widely used in cancer chemotherapy. We report herein the results of a focused medicinal chemistry effort around novel ellipticinium salts which target topoisomerase I and II enzymes with improved solubility. The salts were prepared by reaction of ellipticine with the required alkyl halide and evaluated for DNA intercalation, topoisomerase inhibition and growth inhibition against 12 cancer cell lines. Results from the topoisomerase I relaxation assay indicated that all novel ellipticine derivatives behaved as intercalating agents. At a concentration of 100 μM, specific topoisomerase I inhibition was not observed. Two of the derivatives under investigation were found to fully inhibit the DNA decatenation reaction at a concentration of 100 μM, indicative of topoisomerase II inhibition. N-Alkylation of ellipticine was found to enhance the observed growth inhibition across all cell lines and induce growth inhibition comparable to that of Irinotecan (CPT-11; GI50 1-18 μM) and in some cell lines better than Etoposide (VP-16; GI50 = 0.04-5.2 μM). 6-Methylellipticine was the most potent growth inhibitory compound assessed (GI50 = 0.47-0.9 μM). N-Alkylation of 6-methylellipticine was found to reduce this response with GI50 values in the range of 1.3-28 μM.
Modifications to the Vilsmeier-Haack formylation of 1,4-dimethylcarbazole and its application to the synthesis of ellipticines
Figure represented. An improved method for the preparation of 3-formyl-1,4-dimethylcarbazole, a key intermediate in the synthesis of ellipticine, is presented. Conditions of the Vilsmeier-Haack reaction have been modified to facilitate the production of 3-formyl-1,4-dimethylcarbazole as a major product leading to an overall improvement in yield of ellipticine from 3% to 14%. This approach was also applied to the synthesis of 6-methylellipticine and 9-methoxyellipticine.
Deane, Fiona M.,Miller, Charlotte M.,Maguire, Anita R.,McCarthy, Florence O.
experimental part
p. 814 - 823
(2011/10/04)
Microwave-assisted solid-acid-catalyzed friedel-crafts alkylation and electrophilic annulation of indoles using alcohols as alkylating agents
Alcohols are considered environmentally benign alkylating agents since the only by-product generated in their reactions is water. Herein, we report a microwave-assisted Friedel-Crafts alkylation and electrophilic annulation of indoles using alcohols as al
Kulkarni, Aditya,Quang, Phong,Toeroek, Bela
experimental part
p. 4010 - 4014
(2010/04/02)
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