Synthesis for the Mesomer and Racemate of Thiophene-Based Double Helicene under Irradiation

Abstract

In this work, the racemate and mesomer of the thiophene-based naphthalene-cored double helicenes (<b>1</b>) were obtained efficiently by one-pot photocyclization of 1,1,2,2-tetrakis­(dithieno­[2,3-<i>b</i>:3′,2′-<i>d</i>]­thiophen-2-yl)­ethene in the presence of iodine in dry benzene. The structure of <i>meso</i>-<b>1a</b> was confirmed by single crystal X-ray analysis. The chiral resolution of the racemate was carried out by chiral HPLC, and the chiral properties, such as CD spectra, optical rotations, and half-life of enantiomers were characterized