Table 1. Screening of the Reaction Conditions^a.

entry	variations from the optimal conditionsa	yield of 3aa (%)b
1	none	93
2	CH3CN instead of toluene	79
3	RT instead of 60 °C	69
4	no Te cat.	64
5	no Te cat. at 110 °C	56
6	no Te cat. for 44 h	65
7	Te cat. = PTeZ2	83
8	Te cat. = PTeZ3	93
9	Te cat. = PTeZ4	88
10	Te cat. = PTeZ5	91
11	Te cat. = PTeZ6	81
12	O2 (1 atm) instead of Ag2O	n.r.
13	O2 instead of Ag2O at 110 °C	11
14	DTBP instead of Ag2O	n.r.
15	DTBP instead of Ag2O at 110 °C	41
16	addition of TEMPO (1.5 equiv)	79
17	addition of BHT (1.5 equiv)	44

^aReaction conditions: 1a (0.2 mmol), 2a (0.4 mmol), PTeZ1 (0.02 mmol), Ag₂O (0.2 mmol), toluene (1.5 mL), 60 °C, 16 h.

^bIsolated yields.