The cycloaddition of CO₂ with various epoxides^a.

Entry	Substrate	Product	Time (h)	Yield (%)
1			20 h	>99
2			14 h	>99
3			24 h	>99
4			30 h	>99
5			26 h	>99
6			30 h	>99
7			40 h	95

^aReaction conditions: epoxide (3 mmol), Ti₁₄Cs₂ (100 mg), TBAB (0.5 mmol), CO₂ (1 bar), biphenyl (50 mg), visible light, and 50 °C.