We report studies on the photocatalytic formation of C–S bonds to form benzothiazoles via an intramolecular cyclization and sulfenylated indoles via an intermolecular reaction. Cyclic voltammetry (CV) and density functional theory studies suggest that benzothiazole formation proceeds via a mechanism that involves an electrophilic sulfur radical, while the indole sulfenylation likely proceeds via a nucleophilic sulfur radical adding into a radical cationic indole. These conditions were successfully extended to several thiobenzamides and indole substrates.
Atropisomerism is a type of chirality that is ubiquitous but often overlooked in modern drug discovery. In this Account we discuss studies on leveraging atropisomerism as a design principle in medicinal chemistry, and how this work led to several seemingly disparate projects that began due to synthetic challenges associated with accessing pharmaceutically relevant atropisomers.
Electrophilic aromatic substitution (S
E
Ar) is among the classic routes toward the functionalization of aromatic CH bonds. There are a myriad of functionalities that can be introduced into aromatic systems via S
E
Ar, including but not limited to halogens, perfluoroalkyl, sulfenyl, alkyl, acyl, and nitro substitutions. S
E
Ar has become increasingly common in modern synthetic chemistry as many of the potential products, particularly halogenated arenes, have become important building blocks in drug discovery and other endeavors. Despite its widespread application, S
E
Ar is hindered by several issues that have historically prevented its use on more complex systems. These issues include a reliance on strongly acidic conditions and a lack of regioselectivity. In this article, we will discuss recent advances, from the past vicennial, in S
E
Ar methodology with a focus on new reagents and catalytic strategies that alleviate many of these issues for halogenation, sulfenylation, and perfluoroalkylation.
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