We have developed a novel method for accessing exo adducts with high enantioselectivity in nitrone cycloadditions to enoates. Pyrazolidinones proved to be effective achiral templates in the cycloadditions, providing exo adducts typically in >15:1 selectivity and 90-98% ee. The use of Lewis acids that form square planar complexes, such as copper triflate, was important for obtaining high exo selectivity.
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- Researchers developed a new multi-component assembly method using strain-promoted alkyne-nitrone cycloaddition (SPANC), which allows for the creation of more complex structures, including trifunctional PROTACs.
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