Synergistic effect of hydrogen bonds and π-π interactions of B(C(6)F(5))(3)·H(2)O/amides complex: Application in photoredox catalysis

B(C(6)F(5))(3)·H(2)O has been long recognized as a common Brønsted acid. The lack of X-ray crystal structure of B(C(6)F(5))(3)·H(2)O with other substrates has greatly limited the development of a new catalytic mode. In this work, a complex of B(C(6)F(5))(3)·H(2)O and amide 2-phenyl-3,4-dihydroisoquinolin-1(2H)-one with hydrogen bonds and π-π interactions is characterized by X-ray diffraction. Such noncovalent interactions in solution also exist, as verified by NMR, UV-Vis absorption, and fluorescence emission measurements. Moreover, the mixture of amide 2-phenyl-3,4-dihydroisoquinolin-1(2H)-one and B(C(6)F(5))(3)·H(2)O, instead of other tested Brønsted acids, shows a tailing absorption band in the visible light region (400–450 nm). Based on the photoactive properties of the complex, a photoredox catalysis is developed to construct α-aminoamides under mild conditions.