title: Cobalt-catalyzed negishi cross-coupling reactions of (hetero)arylzinc reagents with primary and secondary alkyl bromides and iodides.
abstract: We report a cobalt-catalyzed cross-coupling of di(hetero)arylzinc reagents with primary and secondary alkyl iodides or bromides using THF-soluble CoCl2 ⋅2 LiCl and TMEDA as a ligand, which leads to the corresponding alkylated products in up to 88 % yield. A range of functional groups (e.g. COOR, CN, CF3 , F) are tolerated in these substitution reactions. Remarkably, we do not observe rearrangement of secondary alkyl iodides to unbranched products. Additionally, the use of cyclic TBS-protected iodohydrins leads to trans-2-arylcyclohexanol derivatives in excellent diastereoselectivities (up to d.r.=99:1).
authors.affiliation: Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, Haus F, 81377 Munich (Germany).
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Hammann
authors.forename: Diana
authors.initials: D
authors.lastname: Haas
authors.forename: Paul
authors.initials: P
authors.lastname: Knochel
keywords: cobalt; cross-coupling; heterocycles; metalation; zinc