Easy access: An unprecedented copper-catalyzed cross-coupling reaction of the title compounds with diboron reagents is described (see scheme; Ts = 4-toluenesulfonyl). This reaction can be used to prepare both primary and secondary alkylboronic esters having diverse structures and functional groups. The resulting products would be difficult to access by other means.
Good solubility alone does not explain the performance of organic ionic bases in the room‐temperature coupling of aryl iodides and even bromides with aliphatic and aromatic amines and N‐heterocycles (NuH; see scheme). Conductivity measurements show that these organic ionic bases, which contain tetraalkylammonium or ‐phosphonium cations, are readily ionized in organic solvents.
Practical catalytic cross-coupling of secondary alkyl electrophiles with secondary alkyl nucleophiles under Cu catalysis has been realized. The use of TMEDA and LiOMe is critical for the success of the reaction. This cross-coupling reaction occurs via an S(N)2 mechanism with inversion of configuration and therefore provides a general approach for the stereocontrolled formation of C-C bonds between two tertiary carbons from chiral secondary alcohols.
A copper-catalyzed reductive cross-coupling reaction of nonactivated alkyl tosylates and mesylates with alkyl and aryl bromides was developed. It provides a practical method for efficient and cost-effective construction of aryl-alkyl and alkyl-alkyl CC bonds with stereocontrol from readily available substrates. When used in an intramolecular fashion, the reaction enables convenient access to various substituted carbo- or heterocycles, such as 2,3-dihydrobenzofuran and benzochromene derivatives.
Palladium‐ and nickel‐catalyzed cross‐coupling recations of unactivated alkyl bromides with diboron reagents have been developed as practical methods for the synthesis of primary and secondary alkylboronic esters. These reactions extend the concept and utility of Pd‐ and Ni‐catalyzed cross‐coupling of aliphatic electrophiles. They also show different substrate selectivity and ligand dependence as compared to the recently reported Cu‐catalyzed borylation reaction.
The first copper-catalyzed/promoted sp(3)-C Suzuki-Miyaura coupling reaction of gem-diborylalkanes with nonactivated electrophilic reagents is reported. Not only 1, 1-diborylalkanes but also some other gem-diborylalkanes can be coupled with nonactivated primary alkyl halides, offering a new method for sp(3)C-sp(3)C bond formation and, simultaneously, providing a new strategy for the synthesis of alkylboronic esters.
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