Synlett

Stereoselective Preparation of Cyclopropylmagnesium Reagents via a Br-Mg Exchange Using i-PrMgCl× LiCl in the Presence of Dioxane

CB Rauhut, C Cervino, A Krasovskiy, P Knochel

Index: Rauhut, Christian B.; Cervino, Christian; Krasovskiy, Arkady; Knochel, Paul Synlett, 2009 , # 1 p. 67 - 70

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Citation Number: 2

Abstract

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 ...