dba=(E,E)-dibenzylideneacetone, Cy=cyclohexyl. We thank Dr. Matthew R. Netherton for helpful discussions and Johnson Matthey Inc. for supplying palladium compounds. Support has been provided by the Deutsche Akademie der Naturforscher Leopoldina (Leopoldina fellowship to J.H.K., BMBF-LPD 9901/8-48), Bristol-Myers Squibb, the National Institutes of Health (National Institute of General Medical Sciences, R01-GM62871), the Natural Sciences and Engineering Research Council of Canada (postdoctoral fellowship to C.D.), and Novartis. Funding for the MIT Department of Chemistry Instrumentation Facility has been provided in part by NSF CHE-9808061 and NSF DBI-9729592.
The window of reactivity is relatively narrow in the first Suzuki cross-coupling of alkyl chlorides with alkyl 9-borabicyclo[3.3.1]nonane (9-BBN) derivatives catalyzed by [Pd2(dba)3] [Eq. (1); dba=(E,E)-dibenzylideneacetone]: whereas good yields are obtained with the ligand tricyclohexylphosphane for ligands that are appreciably larger or smaller, essentially no coupling is observed. As the conditions are compatible with a variety of functional groups, this method introduces a new class of substrates into the family of potential partners in palladium-catalyzed cross-coupling reactions.