Topics in Current Chemistry (2018) 376:46
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4 Use of Supported Catalysts/Reagents in Continuous‑Flow Kinetic
Resolutions
A very promising and interesting application of supported organocatalysts can be
found in the kinetic resolution under continuous flow conditions. One of the main
problems that needs to be faced in developing this strategy is related to the selectivity of the catalyst as well as its wide applicability. Two different approaches, recently
and independently reported by Pericàs’ and Bode’s research groups, will be reported
here. Pericàs reported the first example of acylative kinetic resolution of alcohols
using a polystyrene-supported isothiourea derivative [56]. Supported catalyst 39,
easily prepared in four synthetic steps, and linked to a Merrifield-type resin by a
click reaction, was first tested in batch conditions in order to assess selectivity (up
to 600), recyclability, and versatility. This new and robust catalyst was employed in
a packed-bed reactor using a medium-pressure borosilicate glass column cooled at
0 °C (Scheme 19). Solutions of racemic alcohol (0.4 M) and a mixture of anhydride
(0.24 M) and base (0.26 M) in CHCl 3 were passed through the reactor using syringe
pumps. The kinetic resolution of 1-phenylethanol, with isobutyric anhydride, was
Scheme 19 Supported catalyst for continuous flow kinetic resolution of alcohols (s = selectivity; c = conversion)
46
Reprinted from the journal
1 3
4 Use of Supported Catalysts/Reagents in Continuous‑Flow Kinetic
Resolutions
A very promising and interesting application of supported organocatalysts can be
found in the kinetic resolution under continuous flow conditions. One of the main
problems that needs to be faced in developing this strategy is related to the selectivity of the catalyst as well as its wide applicability. Two different approaches, recently
and independently reported by Pericàs’ and Bode’s research groups, will be reported
here. Pericàs reported the first example of acylative kinetic resolution of alcohols
using a polystyrene-supported isothiourea derivative [56]. Supported catalyst 39,
easily prepared in four synthetic steps, and linked to a Merrifield-type resin by a
click reaction, was first tested in batch conditions in order to assess selectivity (up
to 600), recyclability, and versatility. This new and robust catalyst was employed in
a packed-bed reactor using a medium-pressure borosilicate glass column cooled at
0 °C (Scheme 19). Solutions of racemic alcohol (0.4 M) and a mixture of anhydride
(0.24 M) and base (0.26 M) in CHCl 3 were passed through the reactor using syringe
pumps. The kinetic resolution of 1-phenylethanol, with isobutyric anhydride, was
Scheme 19 Supported catalyst for continuous flow kinetic resolution of alcohols (s = selectivity; c = conversion)
46
Reprinted from the journal