Pauson–Khand cycloaddition reactions of chiral ynamides. Observation of an unusual endo-addition with norbornadiene

Pauson–Khand cycloadditions using chiral ynamides are achieved in modest to good yields with excellent regioselectivity and modest stereoselectivity. An unusual endo addition is found when using norbornadiene and substituted ynamides, leading to cycloadducts that were not observed in previous studies using ynamides or ynamines.