Asymmetric [4 + 2] cycloadditions with 3-furfural derivatives and α-cyano-α,β-unsaturated ketones

Abstract

The dearomatizative dienamine-type intermediates between 2-benzyl-3-furfurals and a chiral secondary amine underwent asymmetric [4 + 2] cycloadditions with α-cyano-chalcone-type substrates, affording tetrahydrobenzofurans having dense substitutions and multiple stereogenic centers with high to outstanding results (up to 92% yield, >99% ee, >19 : 1 dr).