Verma F,
Sahu A,
Singh PK,
Rai A,
Singh M,
Rai VK.
* Guru Ghasidas Vishwavidyalaya, Bilaspur and Jawaharlal Nehru University, New Delhi,
India
Visible-Light Driven Regioselective Synthesis of 1
H-Tetrazoles from Aldehydes through Isocyanide-Based [3+2] Cycloaddition.
Green Chem. 2018;
20: 3783-3789
Key words
cobalt catalysis - photocatalysis - tetrazoles - graphitic carbon nitride - aldehydes
- cycloaddition
Significance
A cobalt-doped polymeric graphitic carbon nitride catalyst (Co@g-C3N4) was prepared by calcination of urea followed by treatment with Co(OAc)2·4H2O in aqueous methanol (eq. 1). Co@g-C3N4 catalyzed the reaction of aldehydes with sodium azide under visible-light irradiation
and air to give the corresponding 5-substituted 1H-tetrazoles in up to 95% yield (eq. 2). The authors propose an isocyanide intermediate,
formed through a Co@g-C3N4-induced photocatalytic 1,2-phenyl migration from C to N.
Comment
Co@g-C3N4 was characterized by means of SEM, XPS, XRD, FTIR, UV-Vis, EDX, TEM, and photoluminescence
analyses. In the reaction of 4-chlorobenzaldehyde with sodium azide, the catalyst
was recovered by filtration and reused four times without significant loss of its
catalytic activity.
