Visible-light-induced C(sp3)-H thiocyanation of pyrazolin-5-ones: a practical synthesis of 4-thiocyanated 5-hydroxy-1H-pyrazoles

A direct, aerobic and visible light photocatalytic approach to synthesize 4-thiocyanated 5-hydroxy-1H-pyrazoles via cross-coupling of pyrazolin-5-ones with ammonium thiocyanate is described. Under redox-neutral and metal-free conditions, a series of 4-thiocyanated 5-hydroxy-1H-pyrazoles could be easily and efficiently obtained in good to high yields by using low-toxicity and inexpensive ammonium thiocyanate as the thiocyanate source.

Automated summary

This study presents a direct, aerobic and visible light photocatalytic approach for synthesizing 4-thiocyanated 5-hydroxy-1H-pyrazoles through the cross-coupling of pyrazolin-5-ones with ammonium thiocyanate. The reaction proceeds under redox-neutral and metal-free conditions, and a series of 4-thiocyanated 5-hydroxy-1H-pyrazoles are obtained easily and efficiently in good to high yields using low-toxicity and inexpensive ammonium thiocyanate as the thiocyanate source.