Transition states dyotropic rearrangements

Dyotropic rearrangement is an uncatalysed process in which two a bonds simultaneously migrate intramolecularly by a dyotropic transition state 202 and has been observed in organosilylhydroxylamine derivatives 201 (equation 59). 

However, the 0-(fluorosilyl)-Af,Af-bis(organosilyl)hydroxylamine 204 undergoes an irreversible rearrangement yielding the isomeric Af-(fluorosilyl)-Af,0-bis(organosilyl) hydroxylamine 205 . The rearrangement proceeds via a dyotropic transition state to yield the hydroxylamine 205. An intermolecular thermal rearrangement with the insertion... 

Since the activation parameters are quite similar to those of the silyl-silyl exchange in silyl silylmethyl ethers (Section II), the authors suggest that the rearrangements in the hydroxylamine series may also occur via a dyotropic mechanism (51). Furthermore, insensitivity to solvent polarity appears to rule out the intermediacy of ions or zwitterions. The possibility of an asymmetric transition state was discussed (51). 

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