The reaction of enals with β-diketones, β-ketoesters, and malonates bearing a β-oxyalkyl substituent at the α-position by oxidative NHC catalysis to provide highly substituted β-lactones is described. Reactions occur with excellent diastereo- and enantioselectivity. The organo cascade comprises two CC bond formations and one CO bond formation. Up to four contiguous stereogenic centers including two fully substituted stereocenters are formed in the cascade.
Keywords: N-heterocyclic carbenes; asymmetric synthesis; cooperative catalysis; organo catalysis; β-lactones.
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