A simple protocol for performing chromium-catalyzed highly diastereoselective alkylations of arylmagnesium halides with cyclohexyl iodides at ambient temperature has been developed. Furthermore, this ligand-free CrCl2 enables efficient electrophilic alkenylations of primary, secondary and tetiary alkylmagnesium halides with readily available alkenyl acetates. Moreover, this chemoselective C‒C coupling
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.