Catalytic enantioselective synthesis of key intermediates for triazole antifungal agents.

[reaction: see text] A short-step synthesis of versatile chiral building blocks for triazole antifungal agents such as ZD0870 and Sch45450 was developed via catalytic enantioselective cyanosilylation of electron-deficient ketones as the key step. High enantioselectivity was produced using a catalyst prepared from Gd(HMDS)(3) and ligand 5 in a 2:3 ratio. This new catalyst preparation method was superior to the previous method using Gd(O(i)Pr)(3) as a metal source. A rationale for the difference is proposed on the basis of structural studies of the catalyst complexes using ESI-MS.

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