DMSO-assisted environmentally benign synthesis of benzo[c]-chromeno[4,3,2-gh]phenanthridines by remote oxidative hetero cross-coupling cyclization and aromatization reaction?

Chemical Communications Pub Date: 2022-04-08 DOI: 10.1039/D2CC01067D

Abstract

An unprecedented metal-free and catalyst-free synthesis of benzo[c]chromeno[4,3,2-gh]phenanthridine derivatives, a class of 1,6-diheterophenalenoid heterocycle, is reported for the first time. The oxidative cross-coupling reaction for the remote cyclization is achieved through the in situ generated o-quinone methide intermediate followed by an electrocyclic ring closure reaction. The aromatization of the cyclohexane ring is achieved by sequential H shift, hydroxylation, and elimination reaction. DMSO-assisted concomitant cyclization and aromatization reactions are also disclosed for the first time.

Graphical abstract: DMSO-assisted environmentally benign synthesis of benzo[c]-chromeno[4,3,2-gh]phenanthridines by remote oxidative hetero cross-coupling cyclization and aromatization reaction
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