Steric and electronic effects on the reduction of O-silylated aromatic ketoximes with borane

4-Methoxy acetophenone oximes substituted at the oxygen with TMS, TBS, TIPS and MDPS groups were reduced with borane–THF obtaining the 4-methoxy-N-ethyl aniline as the principal product, up to a 95% yield in the case of the more hindered TIPS group. The 2-methoxy- and 2,4-methoxyacetophenone O-TBS oximes produced only the rearranged secondary aniline. Reduction of 1-indanone O-TBS oximes afforded only the tetrahydroquinoline, whereas the 2-indanone analog provided only 2-aminoindan.