Gold C–N/C–O coupling without extra oxidants
Cyclometalated gold catalyzes aryl C–N and C–O coupling in air/water by Au(I)/Au(III) oxidative addition, without sacrificial I(III) or F+ oxidants.
Source
Au(iii)-aryl intermediates in oxidant-free C-N and C-O cross-coupling catalysis
Inspect source passages
Gold C–N/C–O coupling without extra oxidants
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t-Butoxide coupling gave 4% yield (2-propoxide 21%).
This trend could be further extrapolated to more sterically demanding alkoxides such as 2-propoxide ( 1ad ) and tert -butoxide ( 1ae ) giving yields of 21% and 4%, respectively (, entries 7 and 8).
Desired C–N product 1ac increased up to 78% after 48 h.
moderate 56% yield of the desired coupling product 1ac was obtained, which could be increased up to 78% after 48 h (, entry 6).
What they did
Authors used [Au(NCMe)IPr]+ with 2-(2-halophenyl)pyridine substrates, coupled alkoxides, water/hydroxide, anilines and amides, isolated C–N cyclometalated Au(III) species, and showed nucleophile acidity controls product identity.
What they found
First oxidant-free gold-catalyzed C–N couplings, plus C–O with aliphatic alcohols and water. Methoxide/ethanol competition favors smaller, more acidic alkoxides; t-butoxide gives only 4%. Aniline coupling reached 78% after 48 h. Air and water are tolerated.
The limits
What it doesn't show
Broad unactivated aryl chloride scope like modern Pd Buchwald–Hartwig is not claimed; many examples use directing 2-pyridyl assistance.
Key terms
- Oxidative addition to Au(I)
- C–X addition giving Au(III) without an external two-electron oxidant.
- Cyclometalated Au(III)–aryl
- Isolable intermediate after intramolecular C–X addition.
- IPr gold cation
- [Au(NCMe)IPr]+ precatalyst used at ~10 mol%.
- Nucleophile acidity
- pKa/basicity that decides which heteroatom outcompetes others (e.g. PhO− vs MeO−).
- Ullmann/Buchwald–Hartwig analogue
- Cu/Pd C–N coupling chemistry that this gold system parallels without extra oxidants.
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These gold C–N couplings avoid:
Common questions
What oxidant is NOT required?
Sacrificial I(III) or F+ sources.
Does gold tolerate air/water?
Yes: absolute tolerance is claimed.
t-Butoxide yield?
About 4%.
What controls C–N vs C–O?
Acidity of the nucleophile.
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