Synthesis of vinyl nonaflates derived from β-ketoesters, 1/4 b-diketones or α-diketones and their palladium-catalyzed cross-coupling reactions with organozinc halides

Article abstract of DOI:10.1016/S0040-4020(98)01221-6

Cyclic and acyclic β-ketoesters 4, a typical cyclic α-diketone 5 and a typical cyclic β-diketone 6 were converted to the corresponding vinyl nonaflates of general formula 7, 8 and 9, respectively, by reaction with 1.2- 1.5 equiv of NaH in DMF at 20-55 °C followed by treatment with 1.15-1.30 equiv of perfluoro-1-butanesulfonyl fluoride at 20 °C. These vinyl nonaflates, which were purified by MPLC on silica gel, proved to be excellent electrophiles in Pd-catalyzed cross-coupling reactions with aryl-, 1-alkynyl- and alkylzinc chlorides. A variety of cyclic and acyclic tetrasubstituted α,β-unsaturated esters which included stereoisomerically pure compounds, a 2-substituted 3-aryl-2-cyclopentenone and naturally-occurring dihydrojasmone were cleanly synthesized by these smooth and selective cross-coupling reactions.