Thus, the reaction of trans-(2-bromocyclopropyl)benzene (1a) with i-PrMgCl˙LiCl in a THF-dioxane (10:1) mixture at 25 ˚C produced the Grignard reagent 2a within eight hours of reaction time. After addition of allyl bromide in the presence of CuCN˙2LiCl [¹¹] (5 mol%) the desired trans-disubstituted cyclopropane 3a was isolated in 74% yield as a single stereoisomer (entry 1 of Table [¹] ). Although the exchange reaction of bromocyclopropane 1a with sec-Bu 2 Mg˙LiCl proceeds in the ...