Directed Copper-Catalyzed Intermolecular Heck-Type Reaction of Unactivated Olefins and Alkyl Halides
作者:Chunlin Tang、Ran Zhang、Bo Zhu、Junkai Fu、Yi Deng、Li Tian、Wei Guan、Xihe Bi
DOI:10.1021/jacs.8b10874
日期:2018.12.12
A new type of intermolecular alkylative olefination of unactivated olefins and alkyl halides has been realized for the first time. This copper-promoted Heck-type reaction employs a directing-group strategy to efficiently produce the coupled alkyl olefin products with excellent regio- and stereoselectivity. A broad substrate scope including 1°, 2°, and 3° alkyl bromides and various nonactivated alkenes
Visible‐Light‐Driven N‐Heterocyclic Carbene Catalyzed γ‐ and
<i>ϵ</i>
‐Alkylation with Alkyl Radicals
作者:Lei Dai、Zi‐Hao Xia、Yuan‐Yuan Gao、Zhong‐Hua Gao、Song Ye
DOI:10.1002/anie.201909017
日期:2019.12.9
The merging of photoredoxcatalysis and N-heterocyclic carbene (NHC) catalysis for γ- and ϵ-alkylation of enals with alkyl radicals was developed. The alkylation reaction of γ-oxidized enals with alkyl halides worked well for the synthesis γ-multisubstituted-α,β-unsaturated esters, including those with challenging vicinal all-carbon quaternary centers. The synthesis of ϵ-multisubstituted-α,β-γ,δ-diunsaturated
elimination to produce exomethylene compounds with a newly formed Csp3–Csp3 bond between tertiary alkyl halides and α-alkylated styrenes, a combination of a Cu(I) salt and a pyridine-based amine ligand (TPMA) is found to be a very efficientcatalystsystem. The yields and regioselectivities were high, and the regioselectivity was found to be dependent on the structure of the alkyl halide, with bulky alkyl
One-Pot Synthesis Using Supported Reagents System: Conversion of β-Dicarbonyl Compounds to α-Thiocyano-β-dicarbonyl Compounds Using CuBr<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub>-KSCN/SiO<sub>2</sub>
作者:Yoshitada Suzuki、Mitsuo Kodomari
DOI:10.1246/cl.1998.1091
日期:1998.11
Transformation of β-dicarbonylcompound 1 to α-thiocyano-β-dicarbonyl compounds 3 in one-pot was achieved by using supported reagents system CuBr2/Al2O3-KSCN/SiO2, in which 1 reacts first with CuBr2/Al2O3 and the product, α-bromo-β-dicarbonyl compound 2 reacts with KSCN/SiO2 to give the final product 3 in good yield.
A novel nickel-catalyzed remote arylation of alkenyl aldehydes triggered by radical alkylation with tertiary α-carbonyl alkyl bromides is described, thus producing a quaternary carbon center containing ketones in promising yields with broad functional group compatibility. Preliminary mechanistic studies suggest that the combination of a 1,n-HAT (n = 5 or 6) from alkyl radicals to aldehyde C–H bonds