Publication Date:
2014-05-13
Description:
Background: Trifluoromethylated alkene scaffolds are known as useful structural motifs in pharmaceuticals and agrochemicals as well as functional organic materials. But reported synthetic methods usually require multiple synthetic steps and/or exhibit limitation with respect to access to tri- and tetrasubstituted CF 3 -alkenes. Thus development of new methodologies for facile construction of C alkenyl –CF 3 bonds is highly demanded. Results: The photoredox reaction of alkenes with 5-(trifluoromethyl)dibenzo[ b , d ]thiophenium tetrafluoroborate, Umemoto’s reagent, as a CF 3 source in the presence of [Ru(bpy) 3 ] 2+ catalyst (bpy = 2,2’-bipyridine) under visible light irradiation without any additive afforded CF 3 -substituted alkenes via direct C alkenyl –H trifluoromethylation. 1,1-Di- and trisubstituted alkenes were applicable to this photocatalytic system, providing the corresponding multisubstituted CF 3 -alkenes. In addition, use of an excess amount of the CF 3 source induced double C–H trifluoromethylation to afford geminal bis(trifluoromethyl)alkenes. Conclusion: A range of multisubstituted CF 3 -alkenes are easily accessible by photoredox-catalyzed direct C–H trifluoromethylation of alkenes under mild reaction conditions. In particular, trifluoromethylation of triphenylethene derivatives, from which synthetically valuable tetrasubstituted CF 3 -alkenes are obtained, have never been reported so far. Remarkably, the present facile and straightforward protocol is extended to double trifluoromethylation of alkenes. Beilstein J. Org. Chem. 2014, 10, 1099–1106. doi:10.3762/bjoc.10.108
Keywords:
electrophilic trifluoromethylating reagentmulti-substituted alkenephotoredox catalysisradical reactiontrifluoromethylation
Electronic ISSN:
1860-5397
Topics:
Chemistry and Pharmacology
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