Dehydrogenative Heck coupling of biologically relevant N-heteroarenes with alkenes: discovery of fluorescent core frameworks

Abstract

A Pd/Cu-catalyzed dehydrogenative Heck coupling is established that allows direct alkenylation of various biologically relevant N-heteroarenes with alkenes. The resulting π-extended alkenylated N-heteroarenes exhibit interesting fluorescent properties and have proven to be potentially useful fluorescent probes for bioimaging.

A concise synthesis of tunable fluorescent 1,3-dihydroisobenzofuran derivatives as new fluorophores

“…Optimizing the donor-acceptor structure also allowed us to red-shift λ E-max and increase the Stokes shift. For instance, compounds C15 and C16 containing trifluoromethyl or cyano group have longer to the electron acceptor (CN) upon excitation by light [17,18].…”

Pd-Catalyzed Intermolecular Dehydrogenative Heck Reactions of Five-Membered Heteroarenes

“…The DHR of indolizines preferentially occurred at the 3-position (Equations (65) and (66) [27] and Equation (67) [106]. When the 3-position was already occupied, the cross-coupling arose in C1 position (Equation (68)) [107].…”

“…The DHR of indolizines preferentially occurred at the 3-position (Equations (65) and (66) [27] and Equation (67) [106]. When the 3-position was already occupied, the cross-coupling arose in C1 position (Equation 68 Using PdCl2/K2CrO4/H2O/O2 in DMF, C1-substituted indolizines underwent cross-coupling with α,β-unsaturated carboxylic acids to produce C3 acylated compounds (Equation (69)) [108].…”

Oxidative Alkenylation of Fused Bicyclic Heterocycles

“…[83] With a bimetallic Pd/Cu catalyst system and the following reaction conditions [Pd(OAc) 2 (2.5 mol-%) as the catalyst precursor, 15 mol-% of CuCl as the co-catalyst, 1.5 equiv. [83] With a bimetallic Pd/Cu catalyst system and the following reaction conditions [Pd(OAc) 2 (2.5 mol-%) as the catalyst precursor, 15 mol-% of CuCl as the co-catalyst, 1.5 equiv.…”