Novel Reagent for Palladium-Catalyzed Cycloaddition with Nitrones

Significance

Hayashi’s group introduced a novel coupling partner for the asymmetric Pd-catalyzed [4+3] cycloaddition. In the presence of chiral phosphoramidite ligand 1, γ-methylidene-δ-valerolactone undergoes cycloaddition with nitrones to furnish adducts in high yields and excellent selectivity. Furthermore, it was shown that reagent 2 exhibits comparably good reactivity towards azamethine imines as well. A significant feature of this protocol is the installment of two contiguous tertiary and quaternary stereocenters.