The syn and anti Steric Course in Bimolecular Olefin‐Forming Eliminations

Earlier evidence led to the view that in bimolecular olefin‐forming eliminations the anti steric course is generally preferred over the syn. Recent experiments, however, show that in some common bimolecular elimination reactions, notably those involving onium bases, syn‐ and anti‐eliminations proceed side by side, the former preferentially leading to the trans‐ and the latter to the cis‐olefins.