Benzaldehyde photoredox heteroarylates amides and ethers

Household CFL light plus benzaldehyde and APS couples heteroarene C–H bonds to amide/ether α-C–H positions without a metal photocatalyst.

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What C–H coupling did the photochemical CDC achieve?

α-Heteroarylation of amides (α to nitrogen) and ethers.

Which C–H types both work?

Amide N-alkyl Csp3–H, ether Cα–H, and formamide carbonyl Csp2–H.

Why is the reaction described as green/practical?

Metal-free, room temperature, household CFL bulbs, ready reagents.

What wavelength region of the CFL is responsible?

Near UV around 364 nm; no reaction in the dark.

Can substoichiometric benzaldehyde still promote the reaction?

Yes—0.5 equivalents gave 90% yield.

What gram-scale isolated yield was obtained?

85%.

How selective is N-methylformamide arylation?

About 8:1 for the carbonyl Csp2–H, 88% yield.

What happens with TEMPO or air?

The reaction is inhibited, supporting a radical mechanism.

Did Ru(bpy)3Cl2 solve the carbamoylation initially?

No—2 mol% gave only 6% of the carbamoylated benzothiazole.

What limitation remains for the coupling partners?

A large excess of amides and ethers is required.

How did TsOH affect benzothiazole coupling?

1 equiv. p-TsOH·H2O improved the yield to 99% by protonating/activating benzothiazole.