obtained by I/Li exchange from the corresponding secondary alkyl iodides undergo two successive transmetalations with Me3SiCH2ZnBr⋅LiBr and CuBr⋅2 LiCl⋅Me2S to provide functionalized secondary alkylcopper compounds with high retention of configuration. These alkylcopper derivatives react further with electrophiles such as alkynyl esters, acid chlorides, allylic chlorides, ketals, ethylene oxide, and 3‐iodocyclopentanone
Diastereoconvergent Negishi Cross-Coupling Using Functionalized Cyclohexylzinc Reagents
作者:Kohei Moriya、Paul Knochel
DOI:10.1021/ol403673e
日期:2014.2.7
Highly diastereoselective Pd-catalyzed cross-coupling reactions of functionalized 2-, 3-, and 4-substituted cyclohexylzinc reagents with aryl, heteroaryl, and alkenyl iodides have been performed under mild conditions. The use of Ruphos (2-dicyclohexylphosphino-2',6'-diisopropoxybiphenyl) as a ligand as well as LiCl and N-ethylpyrrolidone (NEP) as additives leads to especially high diastereoselectivities and displays good functional group tolerance. The stereoselectivity can be explained by assuming that the intermediate palladium moiety occupies an equatorial position of the cyclohexyl ring.