Synthesis 2022; 54(19): 4220-4234
DOI: 10.1055/a-1804-8980
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Synthesis of Diaza[5]helicenes by ortho,ortho′-Fusion of ortho-Terphenyls

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We gratefully acknowledge financial support from the Deutsche Forschungsgemeinschaft (DFG, PO 463/17-1).


Dedicated to Dieter Seebach on the occasion of his 85th birthday

Abstract

Double ortho-fusion in suitably substituted ortho-terphenyls was used for the synthesis of diaza[5]helicenes. Bis(carboxamido)-substituted ortho-terphenyls can be condensed to 5,9- and 6,9-diaza[5]helicenes, where substituents at the 6,10- and 5,10-positions, respectively­, are introduced with the carboxamido groups. While a twofold­ coupling sequence with intermediate protection of one amino group has to be used for 5,9-diaza[5]helicenes, a more concise sequence avoiding the protection leads to 6,9-diaza[5]helicenes. The simple heating of ortho,ortho′-diazidoterphenyls furnishes 5,8-dihydroindolo[2,3-c]carbazoles, i.e., [5]helicenes with alternating benzene and pyrrole rings.

Supporting Information



Publication History

Received: 22 February 2022

Accepted after revision: 22 March 2022

Accepted Manuscript online:
22 March 2022

Article published online:
10 May 2022

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