Allylmagnesium Bromide-Copper(I) Iodide

[1730-25-2]  · C3H5BrMg  · Allylmagnesium Bromide-Copper(I) Iodide  · (MW 145.29)

[7681-65-4]  · CuI  · Allylmagnesium Bromide-Copper(I) Iodide  · (MW 190.44)

(regioselective alkylation;2 stereo- and regioselective addition to propargylic alcohols;3 can add to vinylic oxetanes to give homoallylic alcohols5)

Preparative Methods: allylmagnesium bromide-copper(I) iodide complexes are prepared in situ under anhydrous conditions by reacting Allylmagnesium Bromide (1) with Copper(I) Iodide (2) in varying molar ratios.1

Handling, Storage, and Precautions: use in a fume hood.

Regioselective Alkylation.

Treatment of (1) (1.3 equiv) with octyl iodide in the presence of (2) (10 mol %) gave 1-undecene (eq 1). In the absence of (2) the reaction was slow (22% product after 28 h at 0 °C).2

Stereo- and Regioselective Addition to Propargylic Alcohols.

Primary propargylic alcohols undergo regio- and stereoselective additions of (1) in the presence of 10 mol % of (2) to give allylic alcohols (3) (eq 2).3

Negishi et al. used this methodology in a synthesis of stereodefined exocyclic alkenes (4) (eq 3).4

Synthesis of Homoallylic Alcohols.

Vinylic oxetanes undergo regioselective ring opening to afford homoallylic alcohols (eq 4); preference for the (E) isomer was observed.5

1. For a recent review of organocopper reagents, see: Lipshutz, B. H.; Sengupta, S. OR 1992, 41, 135.
2. Derguini-Boumechal, F.; Lorne, R.; Linstrumelle, G. TL 1977, 1181.
3. Duboudin, J. G.; Jousseaume, B. JOM 1979, 168, 1.
4. Negishi, E.; Zhang, Y.; Cederbaum, F. E.; Webb, M. B. JOC 1986, 51, 4081.
5. Larock, R. C.; Stolz-Dunn, S. K. SL 1990, 341.

Michael N. Greco

The R. W. Johnson Pharmaceutical Research Institute, Spring&thsp;House, PA, USA

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