A boron-based Ireland-Claisen approach to the synthesis of pordamacrine A

A synthetic approach to pordamacrine A that features two key transformations is discussed. The first transformation applies an Ireland-Claisen rearrangement to establish sterically congested vicinal carbon centers. Although a hard enolization technique for accessing the silyl ketene acetal failed, a soft enolization, boron-based reaction was highly successful. The second step involves a proposed cascade palladium-catalyzed biscyclization to construct two carbocycles of the natural product. The overall strategy is presented, demonstrating the challenges of the cyclization events in this complex setting.

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