Intriguing double-inversion stereochemistry in the denitrogenation of 2,3-diazabicyclo[2.2.1]heptene-type azoalkanes: a model mechanistic study in physical organic chemistry

In this review is given a detailed account of the mechanistic elucidation of the unique stereochemical double inversion observed in the nitrogen extrusion of bicyclic azoalkanes. It is shown that the judicious choice of experimental tools and theoretical approaches provides insight into and understanding of this perplexing stereoselectivity. This long-standing mechanistic query serves as an example par excellence of harnessing the structural variation of the DBH-type substrate (internal effects) and the change of medium properties (external effects) to diagnose a complex reaction mechanism. The particular case reviewed here is specific, but the focus in resolving its mechanistic complexities is general and, thus, may be applied to the elucidation of other intricate reaction mechanisms, primarily stereoselective and product-selective organic transformations. Copyright (C) 2004 John Wiley Sons, Ltd.