Presentation description

Helicenes are polycyclic aromatic compounds containing more than three consecutive, ortho-condensed rings. They are valued in materials science applications for their reciprocal optical activity (due to helically chiral enantiomers) in conjunction with their strong fluorescence. Combined, these properties enable the production of materials that emit circularly polarized light. Additionally, extended (multi-ring) helicenes also have promising utilizations in electronics, with the use of cellulose-based biosensors for medical diagnosis being a notable example (Kamel & Khatitan, 2020). Here, the Robert's group has successfully accessed #-aza[5]helicenes and #-aza[6]helicenes with high yields and efficiency. The goal of my project is to successfully construct the aza[7]helicenes using similar methods from the synthesis of #-aza[5]helicenes and #-aza[6]helicenes. The general strategy to prepare polycyclic heteroaromatics first involves a radical halogenation-alkylation or a reductive amination procedure to advance a tertiary amine from a secondary amine. The tertiary amine is then cyclized using a Ni-promoted reaction to access the corresponding biaryl-linked dihydroazepine. Finally, the dihydroazepine intermediate undergoes a deaminative contraction to form the desired polycyclic heteroaromatic. (Kirkeby et al., 2023) So far into the project, I have successfully synthesized the 1-aza[7]helicene and am now currently working on optimizing the yields. The success of my efforts will potentially enable access to larger, 1-aza[8]heliences and 1-aza[9]helicenes.