Room-Temperature Hydrodehalogenation of Halogenated Heteropentalenes with One or Two Heteroatoms

Abstract

The pair NaBH(4)-TMEDA as a hydride source and catalytic PdCl(2)(dppf) in THF prove to be an efficient system for the hydrodehalogenation of bromo(chloro)-heteropentalenes with one or two heteroatoms, while Pd(OAc)(2)/PPh(3) is able to reduce reactive haloheteropentalenes, and PdCl(2)(tbpf) allows the removal of the 2-chlorine from a thiophene ring. The reaction conditions tolerate various functional groups, allowing highly chemoselective reactions in the presence of halide, ester, alkyne, alkene, and nitrile substituents and also showing good efficiency in the regioselective hydrodehalogenation of a variety of polyhalogenated substrates.