Gew-Dibromocyclopropanes

A useM review on organomanganese reagents in organic synthesis has appeared. As described therein, one of the most stable alkyl Mn(II) reagents is trialkyl manganate, MnRs, which can be conveniently prepared as the Li+ or MgBr+ salt and used at 0 °C. These have been utilized for a variety of reactions, such as the stereoselective alkylation of gew-dibromocyclopropanes (Scheme 2), the silylation of acetylenes, and the radical cyclization of allylic ethers. Some of these transformations can be made catalytic. ... 

In this section, the reactions of gew-dibromocyclopropanes and dibromomethylsilanes with trialkylmagnesate reagents are described. Preparation of a chiral secondary Grignard reagent by alkylation of the chiral magnesium carbenoid species is also discussed. 

Grady and Kuivila5 reasoned that it should be possible to carry out a reduction by simply mixing the polysiloxane, an organotin oxide, and substrate. The method was found to be as satisfactory as the conventional method for reduction of alkyl and aryl halides and gew-dibromocyclopropanes. 

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