Diastereoselective Cobalt-Mediated Cross-Couplings of Cycloalkyl Iodides with Alkynyl or (Hetero)Aryl Grignard Reagents.

A highly diastereoselective cross-coupling of variously substituted cycloalkyl iodides with alkynyl and (hetero)aryl Grignard reagents using cobalt(II) chloride has been successfully developed. With the THF-soluble CoCl2·LiCl and the inexpensive ortho-phenanthroline derivative, neocuproine, as a ligand, diastereomeric ratios of up to 99:1 were achieved. A range of functional groups are tolerated in the Grignard reagent (e.g., CF3, Piv, CN, OPiv, NMe2, CO2NEt2, SF5, OTBS).