Abstract
Two alternative reaction conditions developed for allyltrimethoxysilane addition
to N -benzoylhydrazones enable efficient and versatile access to homoallylic α-branched
amines. Aldehyde hydrazones, both aromatic and aliphatic, and ketone hydrazones all
give good yields. One set of conditions employs catalytic amounts of CuCl and tetrabutylammonium
triphenyldifluorosilicate (TBAT); improved yields and reaction times are obtained
at 80 °C in the presence of bis(diphenylphosphino)ethane (dppe) and t -BuOH as additives. The second set of conditions employs 20 mol% TBAT as a fluoride
source in a metal-free catalytic system; here t -BuOH offers only modest improvement, and ambient temperatures are optimal. For example,
under this second set of conditions, the N -benzoylhydrazone from ethyl pyruvate affords the homoallylic tert -alkyl amine adduct in 78% yield.
Key words
addition reactions - allylation - catalysis - hydrazones - silicon
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