Tellurides achiral

Achiral tellurides were used in the catalytic epoxidation of aldehydes by Huang and coworkers in 1990. With diisobutyl telluride as a catalyst (20mol%), various aromatic, heteroaromatic, and non-primary aliphatic aldehydes can be epoxidized directly with aUyhc bromide to the corresponding vinyl epoxides in good yields with predominantly cis-selectivity [59], Later, they successfully extended this method to the cyclopropanation of a,(3-unsaturated ketones with aUyl bromides [60], The asymmetric version of the cyclopropanation was realized by Tang and coworkers in 2003 [61], using salt 43 directly as a catalyst (20mol%) in the reaction of chalcones with silylated aUyl bromide. The desired vinyl cyclopropanes were... 

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