Reaction of Quinoline-5,8-Diones with Selected Charged Phosphorus Nucleophiles

Abstract

The redox reactivity of the two quinoline-5,8-dione derivatives—2-methyl-5,8-dioxo-5,8-dihydroquinoline-7-amine (2a) and N-(2-methyl-5,8-dioxo-5,8-dihydroquinolin-7-yl)acet-amide (2b)—has been demonstrated by their reaction with negatively charged three-coordinated phosphorus nucleophiles, such as R₂P-YM (1a–d, Y = O or lone pair; R = Ph, tBu, OCH₂CMe₂CH₂O, or EtO; M = Li or Na). 1a–d participated in single-electron transfer (SET) to 2a and 2b, generating the radical anions 3 and 4, respectively, together with short-lived phosphorus-centered radical intermediates of type R₂P(= Y)· (5). The radicals 5 dimerize to give R₂P(Y)–(Y)PR₂ (6). Both 3 and 4 are remarkably persistent with half-lives of more than 1 month in THF (tetrahydrofuran) at 300 K.

GRAPHICAL ABSTRACT

Keywords:

• Quinone
• lavendamycin
• EPR spectroscopy
• streptonigrin
• quinoline
• radical

Acknowledgments

We thank the DAAD (Deutscher Akademischer Austausch Dienst) for the award of a fellowship to J. E. Nycz. The GAUSSIAN09 calculations were carried out at the Wrocław Centre for Networking and Supercomputing (WCSS), Wrocław, Poland (http://www.wcss.wroc.pl, grant number 18).