Synthesis of 2-benzimidazolone derivatives in the presence of CS–FPS/Au NPs^a.

Entry	o-Phenylenediamine	Product	Yieldb (%)
1			94
2			90
3			92
4			91
5			95
6			97

^aReaction conditions: o-phenylenediamine derivatives (1 mmol), CS–FPS/Au NPs (50 mg), CO₂ 1.5 MPa, 3 h.

^bIsolated yield.