The elimination of lithium, magnesium and aluminium enolatea of isobutyrates of medium ring cyclanols occurs in a syn fashion. A set of experimental procedures is presented. This elimination seems to be restricted to strained systems. The stereo-chemistry has been determined on stereospecifically deuterated cyclooctanol isobutyrates. The primary isotope effect kH/k2 was 3.0±0.1 and the secondary 1.1. The name β'β elimination is proposed for ...