1-(Trimethylsilyl)vinylmagnesium Bromide-Copper(I) Iodide1

[49750-22-3]  · C5H11BrMgSi  · 1-(Trimethylsilyl)vinylmagnesium Bromide-Copper(I) Iodide  · (MW 203.46)

[7681-65-4]  · CuI  · 1-(Trimethylsilyl)vinylmagnesium Bromide-Copper(I) Iodide  · (MW 190.45)

(reacts with epoxides to give homoallylic alcohols useful for the synthesis of a-methylenebutyrolactones;2 can function as a synthon for epoxides;3,4 adds to D-glyceraldehyde acetonide to give epoxy alcohols and D-threose derivatives3,4)

Preparative Methods: prepared in situ under anhydrous conditions by reacting 1-(trimethylsilyl)vinylmagnesium bromide (1) with Copper(I) Iodide (2) in various molar ratios.

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

a-Methylenebutyrolactone Synthesis.

Epoxides react with (1) in the presence of catalytic amounts of (2) to give homoallylic alcohols (3) (eq 1) which were used in a synthesis of a-methylene lactones (4) (eq 2).2 In the absence of (2) the reaction fails to give the desired homoallylic alcohols (3).

Addition to D-Glyceraldehyde Acetonide: Preparation of Epoxy Alcohols and D-Threose Derivatives.

2,3-O-isopropylideneglyceraldehyde (5) reacts with (1) in the presence of excess (2) to give the syn addition product (6) with high diastereoselectivity (>98:2 syn:anti, eq 3).3,4 Sharpless epoxidation of (6) followed by protodesilylation gave epoxy alcohol (7) (eq 4).3 Alternatively, (6) can be converted to the D-threose derivative (8) by a sequence of three steps: protodesilylation, protection, and ozonolysis.4 Replacement of Copper(I) Cyanide and Methyllithium for CuI in this reaction gives predominantly the anti addition product in 87% yield.

Related Reagents.

2-(3-Trimethylsilyl-1-propenyl)magnesium Bromide-Copper(I) Iodide; Vinylmagnesium Bromide; Vinylmagnesium Bromide-Copper(I) Iodide.

1. For a recent review of organocopper reagents, see: Lipshutz, B. H.; Sengupta, S. OR 1992, 41, 135.
2. Matsuda, I. CL 1978, 773.
3. Sato, F.; Kobayashi, Y.; Takahashi, O.; Chiba, T.; Takeda, Y.; Kusakabe, M. CC 1985, 1636.
4. Kusakabe, M.; Sato, F. CL 1986, 1473.

Michael N. Greco

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

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