Science of Synthesis

Rück-Braun, K.; Freysoldt, T., Science of Synthesis, (2007) 35, 511.

The desymmetrization of meso-epoxides to provide trialkylsilyl-protected bromo alcohols is possible by using a zirconium complex with homochiral amine ligands, i.e. 1,1′,1″-nitrilotripropan-2-ol.[‌45‌] The reaction is carried out in the presence of azidotrimethylsilane and allyl bromide. In the first step, azidotrimethylsilane converts the precatalyst ‌35‌ into a zirconium azide intermediate [Zr2(CO2CF3)(N3)L2]; bromide, derived from allyl bromide, then replaces the azide. The activated bromide subsequently reacts with the epoxides ‌36‌ to give trialkylsilyl-protected bromo alcohols ‌37‌ in good yields and enantioselectivities (‌Scheme 15‌).

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References