Ground-state conformations of non-chelated N-enoylsultams were determined by X-ray-(1, 3) and ¹H-NMR-LIS evidence. Conjugate additions of lithium tri-s-butylborohydride to 1 and 3 followed by O-acylation of the non-isolated “enolates” furnished stereoselectively either (Z) or (E)- O-acyl-N,O-ketene acetals (1 → 2, 3, → 4) depending on the s-cis-/s-trans-conformation of the N-enoylsultams. X-ray diffraction analyses of sultam derivatives 1, 2, 3 and 4 show a pyramidal nitrogen atom. This information provides an insight into the π-face discriminations observed on addition reactions to non-coordinated enoylsultams (e.g. I → II, I → III). N-Enoylsultams I, R² - H undergo remarkably efficient and selective inter- and intramolecular Diels-Alder additions of 1,3- dienes (X-CH₂ or H₂) from the Ca-Re-face I → II, when coordinated with EtAlCl₂ or TiCl₄ [1]