A selenium-coordinated palladium(ii) trans-dichloride molecular rotor as a catalyst for site-selective annulation of 2-arylimidazo[1,2-a]pyridines

Abstract

This report describes the synthesis of a new class of secondary interaction (SeCH⋯Cl)-controlled molecular rotor having a Cl–Pd–Cl rotor spoke attached onto a Se–Pd–Se axle. NMR data acquired at various temperatures established ΔG^‡_298K/ΔG^‡_350K values of 15.5 and 17.2 kcal mol⁻¹ for a roughly 4.5 Å-long rotor. The molecular rotor showed excellent catalytic activity with reverse regioselectivity for annulation of 2-arylimidazo[1,2-a]pyridines (yields: ∼53–78%) with only 1.5 mol% catalyst loading.