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PQ and water oxy-trifluoromethylate enynes
Sunlight-excited phenanthrenequinone turns Langlois’ CF3SO2Na into CF3· and uses water as the oxygen atom to build CF3 benzofurans, benzothiophenes and indoles.
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What photocatalyst enables oxidant-free oxy-trifluoromethylation?
9,10-Phenanthrenequinone (PQ) under visible/sunlight.
Source: Visible-light-induced oxidant and metal-free dehydrogenative cascade trifluoromethylation and oxidation of 1,6-enynes with water · DOI · quote verified
What is the CF3 source?
Langlois’ reagent CF3SO2Na, oxidised by excited PQ.
Source: Visible-light-induced oxidant and metal-free dehydrogenative cascade trifluoromethylation and oxidation of 1,6-enynes with water · DOI · quote verified
Why do O2 and peroxides fail?
They cleave the vinyl C–O bond and give phenol 2a′ instead of benzofuran 2a.
Source: Visible-light-induced oxidant and metal-free dehydrogenative cascade trifluoromethylation and oxidation of 1,6-enynes with water · DOI · quote verified
What yields do phenolic 1,6-enynes give?
Benzofurans 2b–2j in 57–75% under the optimized sunlight conditions.
Source: Visible-light-induced oxidant and metal-free dehydrogenative cascade trifluoromethylation and oxidation of 1,6-enynes with water · DOI · quote verified
How well do thio-enynes cyclize?
Benzothiophenes 4a–4m in 73–36% without gold or palladium.
Source: Visible-light-induced oxidant and metal-free dehydrogenative cascade trifluoromethylation and oxidation of 1,6-enynes with water · DOI · quote verified
What happens to N-tosyl vs N-Boc enynes?
N-Ts substrates detosylate in pot to NH-indoles 67–56%; Boc stays on (10–57%).
Source: Visible-light-induced oxidant and metal-free dehydrogenative cascade trifluoromethylation and oxidation of 1,6-enynes with water · DOI · quote verified
Where does the ketone oxygen come from?
Water: H2^18O gives 18O-labelled 2a (M+H = 307.0821).
Source: Visible-light-induced oxidant and metal-free dehydrogenative cascade trifluoromethylation and oxidation of 1,6-enynes with water · DOI · quote verified
What NMR peak shows H2 evolution?
Singlet at δ 4.57 ppm; D2O gives H–D (δ 4.55 ppm, J = 42.8 Hz).
Source: Visible-light-induced oxidant and metal-free dehydrogenative cascade trifluoromethylation and oxidation of 1,6-enynes with water · DOI · quote verified
What EPR adduct proves CF3·?
t-Butyl-trifluoromethyl nitroxide from MNP: sextet g = 2.0054, a = 12.27 G (dark is silent).
Source: Visible-light-induced oxidant and metal-free dehydrogenative cascade trifluoromethylation and oxidation of 1,6-enynes with water · DOI · quote verified
Is PQ a strong enough oxidant of Langlois’ salt?
Yes: Ered*(3PQ*/PQ·–) = 1.6 V vs Langlois 1.05 V vs SCE; ΔGPET = –12.7 kcal mol–1.
Source: Visible-light-induced oxidant and metal-free dehydrogenative cascade trifluoromethylation and oxidation of 1,6-enynes with water · DOI · quote verified
What quantum yield implies a chain?
φ = 27 product equivalents per absorbed photon.
Source: Visible-light-induced oxidant and metal-free dehydrogenative cascade trifluoromethylation and oxidation of 1,6-enynes with water · DOI · quote verified
Does TEMPO allow product 2a?
No—CF3 is trapped and 2a is not observed.
Source: Visible-light-induced oxidant and metal-free dehydrogenative cascade trifluoromethylation and oxidation of 1,6-enynes with water · DOI · quote verified