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submitted on 17.08.2020 and posted on 18.08.2020by Thomas C. Malig, Lars P.
E. Yunker, Sebastian Steiner, Jason E. Hein
have developed a reaction monitoring platform capable of automated sampling and
online HPLC analysis to generate temporal profiles for reactions performed from
within a glovebox. The device allows for
facile reaction progress analysis to aid in mechanistic studies of air-sensitive
chemical transformations. The platform has demonstrated high reproducibility
regarding sample mixing, dilution, delivery, and analysis. We employed the
sampling platform to acquire temporal profiles for a series of Buchwald-Hartwig
aminations. Parallel coupling reactions using
iodobenzene and bromobenzene both exhibit complex kinetics. A competition
reaction including both aryl halides demonstrated high selectivity for iodobenzene
indicative of catalyst monopoly. The temporal profile for the difunctionalized substrate
1,4-iodobromobenzene was unexpected based a priori and is indicative of
a distinct underlying mechanism. We attribute this unanticipated reactivity to
intramolecular catalysts transfer through the π system as seen in “living”
polymerization transfer catalyst systems. This automated sampling platform has
greatly increased mechanistic understanding by performing only a small subset of