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

Cyclic and acyclic beta-ketoesters 4, a typical cyclic alpha-diketone 5 and a typical cyclic beta-diketone 6 were convened 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 degrees C followed by treatment with 1.15-1.30 equiv of perfluoro-1-butanesulfonyl fluoride at 20 degrees 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 alpha,beta-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. (C) 1999 Elsevier Science Ltd. All rights reserved.