Dedicated to Professor Manfred T. Reetz on the occasion of his 60th birthday Whereas nickel-and palladium-catalyzed methods for crosscoupling aryl and vinyl halides and sulfonates with a range of organometallic reagents have reached a fairly high level of sophistication, [1] comparable progress has not yet been achieved for reactions of alkyl halides and sulfonates. [2] Recently, we and others have begun to address this shortcoming by describing catalysts for certain Suzuki, [3] Negishi, [4,5] Kumada, [6,7] Stille, [8] and Hiyama [9] couplings of primary alkyl electrophiles. With the exception of Suzuki's observation that [Pd(PPh 3 ) 4 ] effects cross-couplings of alkyl iodides with R-(9-BBN), [3a] the palladium-based catalysts that were reported for coupling alkyl electrophiles have all employed a hindered trialkylphosphane (PCy 3 or P(tBu) 2 Me) as the ligand.
To increase the likelihood of expanding the still-limited scope of cross-couplings of alkyl electrophiles, we have been exploring the use of new classes of ligands for these processes. Herein, we establish that, in the presence of alkyldiaminophosphanes (PR(NR' 2 ) 2 ), we can accomplish palladiumcatalyzed Stille cross-couplings of alkyl bromides and iodides not only with vinyl stannanes, but also with aryl stannanes [Eq. ( 1)], a class of reaction partners that are not efficiently coupled by Pd/PR 3 (PR 3 = trialkylphosphane).
As a consequence of the electron-richness and the ready accessibility of alkyldiaminophosphanes (PR(NR' 2 ) 2 ), [10] we
[*] Prof.