Patricia Horrillo-MartÃnez, Kai C Hultzsch, * Adrià Gil, Vicenç Branchadell Base-Catalyzed Anti-Markovnikov Hydroamination of Vinylarenes – Scope,
Limitations and Computational Studies Eur. J. Org. Chem 3311-3325 Abstract: The hydroamination of vinylarenes with primary and secondary
amines was studied with catalytic amounts as low as
2 mol-% of LiN(SiMe3)2/TMEDA. Reactions proceeded readily
at 120 °C in the absence of solvent to give selective anti-
Markovnikov addition. Slow addition was observed at 25 °C
with either electron-deficient p-chlorostyrene or secondary
cyclic amines such as pyrrolidine, piperidine, or morpholine.
Primary amines were prone to a second hydroamination reaction
to form tertiary amine byproducts. The selectivity for
the mono(hydroamination) products could be improved with
a two-fold excess of the amine. KN(SiMe3)2 showed higher
catalytic activity but lower selectivity in comparison to that
of LiN(SiMe3)2, resulting in undesired C–H-activation byproducts.
The mechanism of the lithium-catalyzed hydroamination
and the influence of TMEDA was studied with
density functional theory.
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