Copper(I)‐Catalyzed Enantioselective Synthesis of Chiral Cyclohexenylallenes and Transfer of Axial to Center Chirality by Ytterbium(III) Catalyzed [4+2] Cycloaddition

Chiral cyclohexenylallenes are readily accessed from 1‐enynes, aldehydes and chiral secondary amines in good yields (up to 79% yield) with excellent enantioselectivities (up to 99% ee), through CuI catalyzed the formation of chiral propargylamine intermediates. Subsequent Yb(OTf)3 catalyzed [4+2] cycloaddition reaction of cyclohexylallenes with the dienophiles tetracyanoethylene and diethyl acetylenedicarboxylate afforded the corresponding bicyclic products in 69‐75% yield and 84‐90% ee.