Table 2.

Screening and control experiment of gram-scale [2 + 2] dimerization of α-asarone catalyzed by UCN under white light^a.

Entry	Light	Reactor	Reaction condition variations	Yieldb
1	+	Batch	UCN powdersc	48%
2	+	Flow	UCN@glass fibersd	70%
3	+	Flow	UCN@glass beads	81%
4	−	Flow	In dark	Trace
5	+	Flow	In acetonitrile	2%e
6	+	Batch	UCN@glass beads	53%
7f	+	Flow	UCN@glass beads	87%

^aStandard reaction conditions of flow system: (α-asarone) = 0.167 m, V_CH3NO2 = 60 mL, white LED lamp (0.1 W/cm²), room temperature, air, irradiation time 48 h.

^bIsolated yield.

^cThe amount of UCN is 200 mg.

^dThe amount of UCN coated on glass fibers is 80 mg.

^eConversion from GC-MS.

^fUsing a photoreactor assembled from six paralleled glass tubes with irradiation time 8  h.