科研之友
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摘要
A simple, clean, and efficient approach for the one-pot synthesis of 2-oxindol-3-ylphosphonates has been successfully developed. With 7 mol% loading of the 1,4-diazabicyclo[2.2.2]octane-based ionic liquid catalyst, 2-oxindol-3-ylphosphonates form in good to excellent yields within short times. This tandem reaction involves a phospha-Michael addition to the activated alkenes, which form in situ by Knoevenagel condensation. The corresponding products are easily separated and purified by simple crystallization. The catalyst can be recycled five times without significant activity loss. This approach is readily amenable to large-scale synthesis.
