Synthesis of Unsymmetrical Aza[7]helicenes by One-Pot Wittig–Heck and Photodehydrogenation Sequence

Abstract

An efficient protocol for the synthesis of unsymmetrical aza[7]helicenes has been developed. The bis-styryl-type substrates for regiospecific photodehydrogenative oxidative double cyclization to give helicenes were prepared by a one-pot Wittig–Heck sequence as well as a stepwise procedure. The derivatives were characterized by single-crystal X-ray diffraction analysis and fluorescence spectroscopy.