Cyclopropylmagnesium reagents

The reaction of metals with alkyl halide to form alkylmetal compounds is typical for lithium and magnesium. This so-called direct synthesis was applied to the preparation of both cyclopropyllithium" and derivatives and cyclopropylmagnesium halides under the standard preparative conditions of Grignard reagents without ring cleavage (equation 1). 

Addition of other unsaturated Grignard reagents leads to rather poor product yields. In addition to the 1 1 adducts 3, the formation of higher molecular weight products, e.g. 4, by further addition of the derived cyclopropylmagnesium halide to the starting cyclopropene, was ob-served. ... 

Gassmann and his co-workers have synthesized several fused cyclopropanes [e.g. (14)] by reaction of (12) with excess of alkyl- or aryl-lithium reagents.The cyclopropene (13) is probably an intermediate in these reactions, and it is worth noting that cyclopropylmagnesium iodides [e.g. (16)] are produced by reaction of methylmagnesium iodide with cyclopropenes [e.g. (15)]. ... 

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