Regiochemically Pure 1,6-Ditriflato-Perylene Diimide: Preparation and Transformation

J Org Chem. 2022 Nov 4;87(21):14825-14832. doi: 10.1021/acs.joc.2c01246. Epub 2022 Oct 19.

Abstract

Preparation of regioisomerically pure 1,6-disubstituted perylene diimide (PDI) is not a trivial task owing to the lack of facile synthetic and separation methodologies for the precursors. Herein, we present a simple synthesis for 1,6-ditriflato-PDI (1,6-diOTf-PDI) using 1,6,9,10-tetrabromo-perylene monoimide 1 as the starting material. The selective methoxylation of 1 at the 1,6-position is the key step. Based on a four-step sequence of selective methoxylation, domino carbonylative amidation, demethylation, and triflation, 1,6-diOTf-PDI can be obtained in a satisfactory yield. Moreover, as a building block, 1,6-diOTf-PDIa can readily undergo Suzuki and Sonogashira cross-coupling reactions.