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than a trifluoromethyl iodonium species [Ph–I–CF3]+ as postulated
in previous reports.26a A plausible mechanism is shown in
Scheme 3 and discussed in detail in the ESI.†
14 For biologically relevant 2-pyridinones see: (a) W. S. Hamama,
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N. Ohno, J. Org. Chem., 1988, 53, 4582–4585; (b) For a process
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In conclusion, we have developed an efficient method for the
direct C–H trifluoromethylation of enamides using TMSCF3 as
a convenient, inexpensive and readily available CF3 source. Under
oxidative conditions, a series of hitherto unknown CF3-containing
isoindolinones, isoquinolinones and 2-pyridinones were efficiently
prepared. Application of this protocol for the preparation of
trifluoromethyl analogues of active pharmaceutical ingredients
such as pirfenidone, caffeine and benzothiazine dioxide derivatives
was also established.
Conflicts of interest
20 (a) Using photoredox organocatalyst see: L. Cui, Y. Matusaki, N. Tada,
T. Miura, B. Uno and A. Itoh, Adv. Synth. Catal., 2013, 355, 2203–2207;
(b) Process mediated by Mn(III) as oxidant see: P.-Z. Zhang, C.-K. Li,
G.-Y. Zhang, L. Zhang, Y.-J. Jiang and J.-P. Zou, Tetrahedron, 2016, 72,
3250–3255; (c) Ir photoredox catalyst see: I. Abdiaj, C. Bottecchia,
There are no conflicts to declare.
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