E. Negishi et al., Intermolecular trapping of acylpalladium and related acylmetal derivativeswith active C-H compounds, J MOL CAT A, 143(1-3), 1999, pp. 279-286
The reaction of aryl and alkenyl iodides and bromides with highly acidic ke
tones in the presence of CO (40-45 atm), NEt3 (1-2 equiv.), and 5 mol% of C
l2Pd(PPh3)(2) in DMF at 100 degrees C provides the corresponding enol carbo
xylates formed via trapping of putative acylpalladiums with O-enolates. In
cases where alkenyl halides are used, the initially formed products can cyc
lize to give the corresponding lactones. (C) 1999 Elsevier Science B.V. All
rights reserved.