1. For previous reviews of C-glycosides, please see for example:
2. The Chemistry of C-Glycosides;Levy,1995
3. C-Glycoside Synthesis;Postema,1995
4. Rule 2-Carb-2-1-3, IUPAC Nomenclature of Carbohydrates;Pure Appl. Chem.,1996
5. It is useful in this context to differentiate clearly between three different things that we may call “mechanisms.” The distinction lies above all in the purpose for which it is intended by the authors, and therefore on what standards it should be judged. A mechanistic rationale is a plausible explanation for a single observed result. It should be judged on whether it is reasonable, and needs to be neither predictive nor true, but simply be based on reasonable precedent. A mechanistic model is a mnemonic mechanistic proposal intended to predict the stereochemical outcome of a given class of reactions. It must be simple and predictive but need not be true. Its value, and therefore that on which it must be judged, is on its ability to predict the outcome. This is what is provided here. It is more esthetically pleasing if they are “true,” but this not really germane to the discussion. For example, Lewis structures are clearly not “true” but are nonetheless one of the most useful and essential predictive systems in all of chemistry. The third possibility is a physical organic mechanism, which must be true, and conclusive evidence must be provided for each and every aspect of the proposal. It need be neither simple (it rarely is) nor predictive. A physical organic mechanism is only rigorously true in the specific case and conditions under investigation, and as soon as it is used in another system (prediction), then it is by definition no longer true. There is an essential interplay between physical organic mechanisms (understanding), mechanistic rationales (analysis), and mechanistic models (prediction and manipulation). It is important to clearly define which is being presented, so that it will be interpreted appropriately by the reader. It is difficult to attribute correctly such an established distinction, other than to say that it is not ours. Although our own source is Edwin Vedejs, it most likely originated in the early discussions of Hammett, Hammond, Ingold, Breslow, Wiberg, or Isaacs.