[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.
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).
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.
2-(3-Trimethylsilyl-1-propenyl)magnesium Bromide-Copper(I) Iodide;
Michael N. Greco
The R. W. Johnson Pharmaceutical Research Institute, Spring House, PA, USA