Stereoselective Gridization of Ladder-Type Grids with Four Chiral Centers

Abstract

To address the stereoselective synthesis challenge in π-stacked grids with four chiral centers, we utilized coplanar and highly rigid 11,12-dihydroindeno[2,1-a]fluorene-11,12-diol and 2,2'-bithiophene as synthons, employing Friedel-Crafts gridization (FCG). Leveraging the supramolecular interactions of S···S and π···π within the thiophene moiety, along with the steric effect of the 11,12-dihydroindeno[2,1-a]fluorene scaffold, we successfully achieved the exclusive generation of a single isomer of Ladder-type π-stacked grids (LGs-IF) containing six theoretical isomers. By subsequently substituting 2,2'-bithiophene with thiophene/bithiophene derivatives as synthons, we maintained an exceptionally high level of stereoselectivity. This study introduces a novel approach for the stereo-controlled preparation of grids involving multi-chiral centers.