Rational Design of an Iron-Based Catalyst for Suzuki–Miyaura Cross-Couplings Involving Heteroaromatic Boronic Esters and Tertiary Alkyl Electrophiles
Suzuki–Miyaura cross-coupling reactions between a variety of alkyl halides and unactivated aryl boronic esters using a rationally designed iron-based catalyst supported by β-diketiminate ligands are described. High catalyst activity resulted in a broad substrate scope that included tertiary alkyl halides and heteroaromatic boronic esters. Mechanistic experiments revealed that the iron-based catalyst benefited from the propensity for β-diketiminate ligands to support low-coordinate and highly reducing iron amide intermediates, which are very efficient for effecting the transmetalation step required for the Suzuki–Miyaura cross-coupling reaction.
Byers, Jeffery A.,Crockett, Michael P.,Li, Bo,Wong, Alexander S.
supporting information
p. 5392 - 5397
(2020/03/04)
Quaternary Centers by Nickel-Catalyzed Cross-Coupling of Tertiary Carboxylic Acids and (Hetero)Aryl Zinc Reagents
This work bridges a gap in the cross-coupling of aliphatic redox-active esters with aryl zinc reagents. Previously limited to primary, secondary, and specialized tertiary centers, a new protocol has been devised to enable the coupling of general tertiary systems using nickel catalysis. The scope of this operationally simple method is broad, and it can be used to simplify the synthesis of medicinally relevant motifs bearing quaternary centers.
Chen, Tie-Gen,Zhang, Haolin,Mykhailiuk, Pavel K.,Merchant, Rohan R.,Smith, Courtney A.,Qin, Tian,Baran, Phil S.
The first Suzuki cross-couplings of unactivated tertiary alkyl electrophiles are described. The method employs a readily accessible catalyst (NiBr2·diglyme/4,4′-di-tert-butyl-2,2′-bipyridine, both commercially available) and represents the initial example of the use of a group 10 catalyst to cross-couple unactivated tertiary electrophiles to form C-C bonds. This approach to the synthesis of all-carbon quaternary carbon centers does not suffer from isomerization of the alkyl group, in contrast with the umpolung strategy for this bond construction (cross-coupling of a tertiary alkylmetal with an aryl electrophile). Preliminary mechanistic studies are consistent with the generation of a radical intermediate along the reaction pathway.
Zultanski, Susan L.,Fu, Gregory C.
supporting information
p. 624 - 627
(2013/03/14)
Process for introduction of styrenes in side chain of substituted aromatic compounds
A process for introduction of styrenes in the side chain of substituted aromatic compounds, said side chain containing at least one hydrogen atom in the α-position thereof, is disclosed, comprising reacting the styrenes and the substituted aromatic compounds in the presence of (A) an alkali metal and (B) a compound containing a benzyloxy group or alkyl and/or aryl-substituted benzyloxy group. Use of (A) and (B) as a reaction accelerator permits to introduce the styrenes in the side chain of the substituted aromatic compounds in high yield and selectivity.
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(2008/06/13)
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