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oai:ojs.www.eurjchem.com:article/976 2014-06-30T08:07:07Z eurjchem:ART driver

Friedel-Crafts chemistry: Part 41. A new facile synthesis of indeno[1,2-c] pyrazoles, 2H-benzo[g]indazoles and benzo[6,7]cyclohepta[1,2-c]pyrazoles via Friedel-Crafts ring closures Abd El-Aal, Hassan Abdou Kotb El-Khawaga, Ahmed Mahmoud Abdel Mageed Khalaf, Ali Ali Benzo[g]indazole Heteropolycycles Heteroarylalkanols Indeno[1 2-c]pyrazole Friedel-Crafts ring closures Benzo[6 7]cyclohepta[1 Expedient and novel alternative synthesis of some fused heteropolycycles containing pyrazole moiety is described. A series of indeno[1,2-c]pyrazoles, 2H-benzo[g]indazoles and benzo[6,7] cyclohepta[1,2-c]pyrazoles were prepared by Friedel-Crafts ring closure of suitable synthesized carboxylic acids and alkanols in the presence of AlCl3/CH3NO2 or P2O5 or PPA (polyphosphoric acid) catalysts. The precursor acids were obtained by utilizing KMnO4 oxidation of the corresponding aldehyde, alkylations of diethyl malonates and Perkin type approaches, whereas starting alkanols were smoothly obtained by reaction of carboxylic acid ester with Grignard reagent. To exemplify, cyclizations of 5-chloro-1,3-diphenyl-1H-pyrazole-4-carboxylic acid (6) were accomplished using the above catalysts afforded 3-chloro-2-phenylindeno[1,2-c]pyrazol-4(2H)-one (1b). Similarly, cyclization of the 2-(5-chloro-1,3-diphenyl-1H-pyrazol-4-yl)propan-2-ol (8) by a Friedel–Crafts-type ring closure afforded the 3-chloro-2,4-dihydro-4,4-dimethyl-2-phenylindeno[1,2-c]pyrazole (1a). Atlanta Publishing House LLC 2014-06-30 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion application/pdf https://www.eurjchem.com/index.php/eurjchem/article/view/976 10.5155/eurjchem.5.2.277-286.976 European Journal of Chemistry; Vol. 5 No. 2 (2014): June 2014; 277-286 2153-2257 2153-2249 eng https://www.eurjchem.com/index.php/eurjchem/article/view/976/pdf_976