作业帮求分析化学有关的诺贝尔奖工作原始文献
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求分析化学有关的诺贝尔奖工作原始文献
求分析化学有关的诺贝尔奖工作原始文献
求分析化学有关的诺贝尔奖工作原始文献
Since the formation of a titanacyclopropane en route to
cyclopropylamines can only occur with alkylmagnesium
halides that contain a b-hydrogen atom, Grignard reagents
without b-hydrogens appeared to be the most promising
reagents for the synthesis of primary tert-alkylamines
from nitriles (Scheme 1). Thus propionitrile (1a), phenylmagnesium
bromide (2) and Ti(Oi-Pr)4 were chosen to
optimize the reaction conditions. In the protocol for the
synthesis of cyclopropylamines,10 Ti(Oi-Pr)4 is already
present in the diethyl ether solution of a nitrile, before two
equivalents of the Grignard reagent are added. As this did
not appear to be optimal for the synthesis of primary tertalkylamines,
the Grignard reagent was added before
Ti(Oi-Pr)4. With 2 equivalents of PhMgBr, 0.1 equivalent
of Ti(Oi-Pr)4, and 1 equivalent of propionitrile (1a), the
primary tert-alkylamine 8a was not formed at all. With an
equimolar quantity of Ti(Oi-Pr)4, the amine 8a was produced
in a low yield (11%) but with 1 equivalent of Ti(Oi-
Pr)4 and 3 equivalents of the Grignard reagent 2, a 60%
yield of 8a was obtained. Monitoring of the reaction by
workup of aliquots of the reaction mixture showed that the
first addition of 2 to form the N-magnesio derivative of the
corresponding imine was rapid, whereas the subsequent
second addition of the Grignard reagent 2 required heating
under reflux for up to 24 hours. In tetrahydrofuran instead
of diethyl ether, the amine 8a was formed in a very low
yield, if at all.
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