Controlled Trifluoromethylation Reactions of Alkynes through Visible‐Light Photoredox Catalysis
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For recent reports on selective reactions see:
For recent reviews on synthetic methods for trifluoromethylation see:
For selected examples of trifluoromethylation reactions see:
For recent reviews on visible‐light‐induced photocatalysis see:
Noël T., 2013, Chim. Oggi, 31, 10
For examples of visible‐light‐driven trifluoromethylation reactions see:
For examples of alkenyl–trifluoromethylation reactions see:
For iodoperfluoroalkylations of alkynes see:
Recently Stephenson and co‐workers reported a visible‐light‐induced radical reaction of alkynes with [Ru(bpy)3]Cl2and C8F17I that produced the C8F17‐substituted alkenyl iodide with a selectivity ratio of approximately 2:1; see Ref. [6e].
For trifluoromethylations of terminal alkynes see:
The [NR3].+species formed by the photocatalytic pathway bears acidic α‐hydrogen atoms; therefore it can be used as the hydrogen donor. For examples of hydrogen abstraction from aminium radical cations see:
For stereochemical aspects of reactions with propargylic alcohols see:
Isolated2 a(Scheme 1) was subjected to the conditions described in Scheme 2. See the Supporting Information Scheme S1.
Alkenyl iodide 2 awas detected during the reaction of1 a see the Supporting Information Figure S1 (kinetic studies of the reaction with1 a).
It is likely that the reaction proceeded through an alkynyl iodide as the intermediate. For experimental details see the Supporting Information Scheme S2. A plausible mechanism for the trifluoromethylation of alkynes is proposed in Figure S2.