Superelectrophilic-Initiated C-H Functionalization at the β-Position of Thiophenes: A One-Pot Synthesis of trans-Stereospecific Saddle-Shaped Cyclic Compounds

J Org Chem. 2019 Sep 6;84(17):10701-10709. doi: 10.1021/acs.joc.9b01233. Epub 2019 Aug 12.

Abstract

Superelectrophilic-initiated direct C-H functionalization of thiophenes at the β-position was developed. A series of trans-stereospecific [2,1-a]-IF-thiophene-fused cyclic compounds (4) with saddle-shaped structure were prepared in 17-30% yields through a one-pot superelectrophilic Friedel-Crafts reaction of dihydroindenofluorene with thiophene derivatives. From the crystal packing analyses of 4a, its skeleton shows both strong intermolecular π-π stacking and C-H···π stacking. Furthermore, the ring-dependent photophysical properties of 4 were confirmed by UV-vis absorption and photoluminescence spectroscopy as well as through the study of their fluorescence quantum yield.