Beilstein J. Org. Chem.2014,10, 1397–1405, doi:10.3762/bjoc.10.143
the dehydrationofoximes 12 to form nitriles 13.
Capitalizing on the fact that 1 is formed as a byproduct from 3a,b in each of these reactions, Denton and co-workers have recently combined the Masaki–Fukui reaction with many of the functional group transformation outlined in Scheme 2, in one-pot
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Graphical Abstract
Scheme 1:
The Masaki–Fukui reaction and halophosphonium salt reduction.
Beilstein J. Org. Chem.2013,9, 1698–1704, doi:10.3762/bjoc.9.194
X-ray photoelectron spectroscopy (XPS). XPS revealed the presence of one gallium per 2–3 styrene sulfonate groups of the polymer brushes. The catalytic activity of the Lewis acid-functionalized brushes in a microreactor was demonstrated for the dehydrationofoximes, using cinnamaldehyde oxime as a
model substrate, and for the formation of oxazoles by ring closure of ortho-hydroxy oximes. The catalytic activity of the microreactor could be maintained by periodic reactivation by treatment with GaCl3.
Keywords: dehydrationofoximes; flow chemistry; gallium; microreactors; Lewis acid catalysis
substrate scope of the dehydrationofoximes was extended using the same reaction conditions as above (Table 2). 4-Nitrobenzaldehyde oxime (3, Table 2, entry 1) resulted in a conversion of 62% within 13 min reaction time, while for the batch reaction, using gallium(III) triflate as a catalyst, 16 h at 120
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Graphical Abstract
Scheme 1:
Gallium-catalyzed dehydration of cinnamaldehyde oxime (1).