Synthesis of substituted alkanes
A slow and regular addition of primary alkyl and aryl Grignard reagent enables a high-yielding copper-catalyzed alkylation with alkyl bromides in the absence of ligands. With secondary and tertiary alkyl Grignard reagents, the presence of benzonitrile as a very simple ligand is sufficent. A copper-catalyzed alkylation of organolithium compounds was also studied.
G. Cahiez, O. Gager, J. Buendia, Synlett, 2010, 299-303.
A Pd-NHC catalytic system has been developed, that is capable of cross-coupling various unactivated, primary bromides and alkyl organozinc reagents in high yield at room temperature.
N. Hadei, E. A. B. Kantchev, C. J. O'Brien, M. G. Organ, Org. Lett., 2005, 7, 3805-3807.
The use of 2% Pd2(dba)3/8% PCyp3/NMI in THF/NMP at 80°C achieves the cross-coupling of a range of β-hydrogen-containing primary alkyl iodides, bromides, chlorides, and tosylates with an array of alkyl-, alkenyl-, and arylzinc halides. This method tolerates various functional groups.
J. Zhou, G. C. Fu, J. Am. Chem. Soc., 2003, 125, 12527-12530.
A cobalt-catalyzed cross-coupling of alkyl (pseudo)halides with alkyl Grignard reagents proceeds via an ionic mechanism in the presence of 1,3-butadiene as a ligand precursor and LiI in high yields and high selectivities. Sterically congested quaternary carbon centers could be constructed by using tertiary alkyl Grignard reagents. This reaction is compatible with various functional groups.
T. Iwasaki, H. Takagawa, S. P. Singh, H. Kuniyasu, N. Kambe, J. Am. Chem. Soc., 2013, 135, 9604-9607.
In a practical catalytic cross-coupling of secondary alkyl electrophiles with secondary and primary alkyl nucleophiles under Cu catalysis, the use of TMEDA and LiOMe is critical for the success of the reaction. This cross-coupling reaction occurs via an SN2 mechanism with inversion of configuration.
C.-T. Yang, Z.-Q. Zhang, J. Liang, J.-H. Liu, X.-Y. Lu, H.-H. Chen, L. Liu, J. Am. Chem. Soc., 2012, 134, 11124-11127.
In stereoconvergent, arylamine-directed alkyl-alkyl Suzuki cross-coupling reactions, structure-enantioselectivity studies are consistent with the nitrogen, not the aromatic ring, serving as the primary site of coordination of the arylamine to the catalyst.
Z. Lu, A. Wilsily, G. C. Fu, J. Am. Chem. Soc., 2011, 133, 8154-8157.
Carbamates and sulfonamides serve as directing groups in Ni-catalyzed asymmetric Suzuki reactions for cross-coupling of unactivated alkyl electrophiles. Racemic secondary bromides and chlorides undergo C-C bond formation in a stereoconvergent process in good ee at room temperature in the presence of a commercially available Ni complex and chiral ligand.
A. Wilsily, F. Tramutola, N. A. Owston, G. C. Fu, J. Am. Chem. Soc., 2012, 134, 5794-5797.
Screening of a 15-member library of phosphaadamantane ligands has allowed for the rapid determination of the most suitable ligand for facilitating Suzuki-type couplings of alkyl halides or tosylates containing β-hydrogens with either boronic acids or alkylboranes.
T. Brenstrum, D. A. Gerristma, G. M. Adjabeng, C. S. Frampton, J. Britten, A. J. Robertson, J. McNulty, A. Capretta, J. Org. Chem., 2004, 69, 7635-7639.
The reaction of 1,1-bis(pinacolboronate) esters with alkyl halides promoted by metal alkoxides provides organoboronate compounds via alkoxide-induced deborylation and generation of a boron-stabilized carbanion.
K. Hong, X. Liu, J. P. Morken, J. Am. Chem. Soc., 2014, 136, 10581-10584.