Aliphatic compounds substituted with medicinally importantt rifluoromethylthio (SCF 3 )a nd trifluoromethylselenyl (SeCF 3 )g roups weres ynthesized directly from alcohols by using the new benzothiazolium salts BT-SCF 3 and BT-SeCF 3 .T hese bench-stable fluorine-containing reagents are facile to use and can be prepared in two steps from non-fluorinated heteroaromatic startingm aterials. The metal-free deoxytrifluoromethylthiolation process using BT-SCF 3 proceeds under mild conditions and the similarly efficient trifluoromethylselenylationr eactions using BT-SeCF 3 are, to the besto fo ur knowledge, the first reported examples of this transformation.Scheme1.a) Benzothiazolium Reagents BT-SCF 3 and BT-SeCF 3 .b )Previously reported deoxytrifluoromethylthiolation reactionso fa liphatic alcohols. c) This work: Deoxytrifluoromethylthiolation and selenylation of alcohols with BT-SCF 3 and BT-SeCF 3 .[bmim] = 1-Butyl-3-methylimidazolium.[a] S.Scheme2.a) Two-step synthesisofBT-SCF 3 and its applicationi nthe deoxytrifluoromethylthiolation of aliphatic alcohol 2a.b)Likely reaction mechanism via 2-alkoxybenzothiazolium salt 4.
The combination of N-heterocyclic carbene (NHC)-organocatalysis with photochemical activation can lead to unprecedented reaction pathways not observed without light. A selection of dual catalytic systems merging NHCs with photoredox catalysis, for example, have leveraged the ability of NHCs to stabilize intermediate radical species and facilitate single electron transfer events. Furthermore, NHCs can transiently modulate the photochemical properties of a substrate and enable direct absorption of otherwise photoinactive organic compounds. In this Concept article, the recent advances in this rapidly developing field are summarized. For each transformation, a particular focus is placed on the mechanistic aspects of the process while key features that highlight the synthetic potential of the light mediated NHC organocatalysis are presented.
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