Novel Rh Catalysis in Cross-Coupling between Alkyl Halides and Arylzinc Compounds Possessing ortho-COX (X = OR, NMe2, or Ph) Groups
摘要:
[GRAPHICS]Rh-dppf was found to be an efficient catalyst for the cross-coupling between primary alkyl halides bearing beta-hydrogens and arylzinc compounds possessing carbonyl groups such as ester, amide, or ketone at the ortho position. Various functional groups such as ester, nitrile, or acyloxylate moieties on the halides were tolerated under the catalysis conditions. Arylzinc compounds free of ortho-carbonyl groups reacted well with ethyl 3-iodopropanoate, suggesting that the essential intramolecular interaction between carbonyl groups and Rh promotes the reductive elimination.
The γ C–H amination of carboxylic acid presents a promising and sustainable strategy for synthesizing high-value pharmaceutical chemicals. Radical reaction pathways initiated by aroyloxy radical-involved hydrogen atom transfer (HAT) provide diverse but challenging opportunities for remote C–H functionalization. In this report, the first example of intramolecular γ C–H amination of carboxylic acids
carbon chain with carbocyclic (phenyl and cyclopropane) and heterocyclic (epoxide and dioxolane) moieties were prepared and their cyclizations in the presence of bis(collidine)iodonium(I) and -bromonium(I) hexafluorophosphates as electrophiles were studied. Oxocanes were obtained in modest to good yields when a rigid cyclic moiety (cyclopropane or phenyl) was present in the chain, while yields of cyclizations
[GRAPHICS]Rh-dppf was found to be an efficient catalyst for the cross-coupling between primary alkyl halides bearing beta-hydrogens and arylzinc compounds possessing carbonyl groups such as ester, amide, or ketone at the ortho position. Various functional groups such as ester, nitrile, or acyloxylate moieties on the halides were tolerated under the catalysis conditions. Arylzinc compounds free of ortho-carbonyl groups reacted well with ethyl 3-iodopropanoate, suggesting that the essential intramolecular interaction between carbonyl groups and Rh promotes the reductive elimination.