Thermal Rearrangement of Bis- and Tris Silyl hydroxylamines

Systematic studies of related rearrangements in tris(silyl) hydroxylamines have been reported by West and co-workers (50, 51), the results of which are described below. 

A series of hydroxylamines 41a-d and 42a-d having variously substituted silyl groups were synthesized (57). 

Rate Data for Dyotropic Silyl-Silyl Exchange in Hydroxylamines 

Rearrangement k X 10- (sec ) Tempera- ture CC) K (kcal/mole) (kcal/mole) A5t (e.u.) 

Thermolyses of 41a or 41b do not afford crossover products (51). Thus 41e is not formed, proving 100% intramolecularity. In contrast to Eq. (9), this single experiment shows that the two exchanging silyl groups stay together and do not depart from the substrate. 

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