Asymmetric Diels ‐ Alder Reaction of 1‐Methoxybuta‐1,3‐diene with (2 R )‐ N ‐Glyoxyloylbornane‐10,2‐sultam

Starting from sultam 1 , the chiral dienophile (2 R )‐ N ‐glyoxyloylbornane‐10,2‐sultam ( 4 ) was readily prepared. Non‐catalyzed atmospheric‐ and high‐pressure as well as [Eu(fod) 3 ]‐promoted [4 + 2] cycloadditions of 1‐methoxy‐buta‐1,3‐diene ( 5 ) to chiral dienophile 4 , leading with high asymmetric induction to 6‐methoxy‐3,6‐dihydro‐2 H ‐pyran‐2‐yl derivatives 6 – 9 , are described. The extent and direction of asymmetric induction in these reactions were established by 1 H‐NMR analysis and chemical correlation, respectively. Stereochemical models for both non‐catalyzed and [Eu(fod) 3 ]‐promoted reactions are proposed.