During the research on the Pd-catalyzed intramolecular cyclization reaction via C-H activation, the dehalogenation
of 3-halo-2(5H)-furanones is unexpectedly discovered. Under the optimized conditions without any special anaerobic
and anhydrous treatments, using N,N-diisopropylethylamine (DIPEA) simultaneously as hydrogen source and base, the
reactions of 27 substrates with less Pd catalyst (5 mol% Pd(PPh3)4) usually give higher yields (70-99%, mostly over 82%).
Especially for 3-halo-2(5H)-furanone substrates simultaneously containing aryl halide structure, this kind of Pd-catalyzed
dehalogenation has good selectivity. After the selectivity is explained via the substrate theoretical calculation, a possible
reaction mechanism of the Pd-catalyzed dehalogenation is proposed. These novel investigations provide an efficient, simple,
practical and selective Pd-catalyzed dehalogenation method for the non-aromatic halide substrates with many
different functional groups.
Keywords: Amines, chemoselectivity, dehalogenation, 2(5H)-Furanone, halide, mass spectroscopy, palladium.
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