Synthetic Strategies in the Preparation of Phenanthridinones

Phenanthridinones are important heterocyclic frameworks present in a variety of complex natural products, pharmaceuticals and displaying wide range of pharmacological actions. Its structural importance has evoked a great deal of interest in the domains of organic synthesis and medicinal chemistry to develop new synthetic methodologies, as well as novel compounds of pharmaceutical interest. This review focuses on the synthesis of phenanthridinone scaffolds by employing aryl-aryl, N-aryl, and biaryl coupling reactions, decarboxylative amidations, and photocatalyzed reactions.

Formal Electrophilic Phenylation Reaction with Tropylium Ion

Arylation reaction is an important transformation in synthetic chemistry as aryl building blocks are ubiquitous in valuable organic frameworks. Traditionally, this type of reaction has been carried out either via biaryl coupling reactions or with the use of reactive intermediates such as arynes or aryl radicals. Direct electrophilic arylation reactions have been rarely reported in literature, as the required arenium building blocks are often unstable or inaccessible. To develop a new strategy for such transformation, we herein introduce the development of a formal phenylation reaction, which proceeds via an electrophilic cycloheptatrienylation with tropylium ion, followed by an oxidative ring-contraction.

Formal Electrophilic Phenylation Reaction with Tropylium Ion

Arylation reaction is an important transformation in synthetic chemistry as aryl building blocks are ubiquitous in valuable organic frameworks. Traditionally, this type of reaction has been carried out either via biaryl coupling reactions or with the use of reactive intermediates such as arynes or aryl radicals. Direct electrophilic arylation reactions have been rarely reported in literature, as the required arenium building blocks are often unstable or inaccessible. To develop a new strategy for such transformation, we herein introduce the development of a formal phenylation reaction, which proceeds via an electrophilic cycloheptatrienylation with tropylium ion, followed by an oxidative ring-contraction.