The Pd(II)âSDP-catalyzed first enantioselective intramolecular cyclization of α,α-disubstituted γ-alkynoic acids is described. This 5-exo-dig cyclization afforded dihydrofuran-2(3H)-ones bearing a chiral quaternary carbon center in excellent yields with enantioselectivities up to 71%. A mechanism involving palladium(II) species is proposed to rationalize the outcome of the reaction.
介绍了 Pd(II)â
SDP 催化的δ,δ-二取代δ-炔酸的首次对映选择性分子内环化。这种 5-exo-dig 环化反应以极好的收率获得了含有手性季碳中心的二氢
呋喃-2(3H)-酮,对映选择性高达 71%。提出了一种涉及
钯(II)物种的机理,以合理解释反应的结果。