Chalcogenides rearrangement

The hydroniumm ion-catalysed vinyl alcohol-acetaldehyde isomerization has been investigated627 via ab initio MO calculations, and the results have supported the stepwise mechanism shown in Scheme 125. A theoretical study of the tautomeric rearrangements in mono- and di-chalcogenide analogues of formic acid, [HC(X)YH ... 

Enantioselective [2,3]Sigmatropic Rearrangement Producing Optically Active Homoallylic Chalcogenides... 

Chalcogenide oxidation. The oxidation and selenoxide elimination sequence is applicable to the generation of functionalized alkenes which are prone to Claisen rearrangement. Medium-sized rings including tetrahydroazepin-2-ones are accessible in this manner. ... 

The structural rearrangement processes responsible for enthalpy relaxation tend to be very slow at room temperature, where little thermal energy is available to activate molecular reorientations. Equation [2.4] indeed shows that the structural relaxation time increases exponentially with decreasing temperature. Hence these processes are typically hard to observe on a laboratory timescale. However, chalcogenides also possess the unique property of photosensitivity, which offers another means of inducing structural... 

Figure 2.17 Schematic representation of photostructural changes in a chalcogenide glass, (a] Photoexcitation of a valence electron leads to a net structural rearrangement in a floppy network, (b] Photoexcitation leaves a rigid network unchanged (after [77]].

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