Zusammenfassung
A generally applicable method for the direct 3-N-arylation of flavins using arylboronic acids and copper acetate was developed. The reaction conditions were optimized considering the lability of flavins in basic conditions and thermal heating. Donor- and acceptor-substituted arylboronic acids were used yielding 3-N-arylflavins in moderate to good yields by C(aryl)-N(imide) bond formation. UV and ...
Zusammenfassung
A generally applicable method for the direct 3-N-arylation of flavins using arylboronic acids and copper acetate was developed. The reaction conditions were optimized considering the lability of flavins in basic conditions and thermal heating. Donor- and acceptor-substituted arylboronic acids were used yielding 3-N-arylflavins in moderate to good yields by C(aryl)-N(imide) bond formation. UV and fluorescence measurements indicate an orthogonal orientation of the additional aromatic substituent to the flavin ring system. The arene substituent is not electronically coupled to the flavin π-system in the ground state, but electron-rich arene substituents in 3-N position significantly reduce the flavin emission intensity.