Palladium-Catalyzed Inter- and Intramolecular Cross-Coupling Reactions of B-Alkyl-9-borabicyclononane Derivatives with 1-Halo-1-alkenes or Haloarenes. Syntheses of Functionalized Alkenes, Arenes, and Cycloalkenes via a Hydroboration-Coupling Sequence

Article abstract of DOI:10.1021/ja00183a048

The cross-coupling reaction of B-alkyl-9-borabicyclo<3.3.1>nonanes (B-R-9-BBN), readily obtainable from alkenes by hydroboration, with 1-halo-1-alkenes or haloarenes in the presence of a catalytic amount of PdCl2(dppf) and bases, such as sodium hydroxide, potassium carbonate, and phosphate, gave the corresponding alkenes or arenes.Because the reaction is tolerant of a variety of functionalities on either coupling partner, stereochemically pure functionalized alkenes and arenes can be obtained under mild conditions.The utility of the reaction was demonstrated by the stereoselective synthesis of 1,5-alkadienes (7 and 8) and the extension of a side chain in a steroid (11).The hydroboration of haloalkadienes (12), followed by the intramolecular cross-coupling, gave a short-step procedure for synthesis of cycloalkenes, benzo-fused cycloalkenes, and exocyclic alkenes (14 and 16).