Visible-light-induced photocatalytic intermolecular cyclization for synthesis of 2,2-diarylchromanes

The photocatalytic cyclization of salicylaldehydes with 1,1-diarylalkenes for the synthesis of 2,2-diarylchromanes has been developed. The catalytic amount of Ir photocatalyst proceeds the cyclization to give the various 2,2-diaryl chromanes under irradiation with blue LEDs. The obtained 2,2-diarylchromanes exhibit noticeable free-radical-scavenging activities, which have been largely unexplored. Notably, the chromane can convert to 2,2-diaryl-2H-naphtho[1,2-b]pyran bearing strong electron withdrawing groups, which are found in various photochromic materials. Thus, the present reaction constitutes a promising tool for the synthesis of functional materials and biologically active compounds.