Table 1. Optimization of catalyst conditions for cyclization reaction in water at room temperature.
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| Entry | Conditions | Result |
| 1 | LAuCl (1000 ppm) + AgBF4 (1000 ppm) | NR |
| 2 | LAuCl (1000 ppm) + AgOTf (1000 ppm) | NR |
| 3 | LAuCl (1000 ppm) + AgSbF6 (1000 ppm) | NR |
| 4 | LAuCl (1000 ppm) + AgBF4 (1000 ppm) + TFA (1 equiv.) | 56% (5 d) |
| 5 | LAuCl (1000 ppm) + AgOTf (1000 ppm) + TFA (1 equiv.) | Trace |
| 6 | LAuCl (1000 ppm) + AgSbF6 (1000 ppm) + TFA (1 equiv.) | 71% (4 d) |
| 7 | LAuCl (1000 ppm) + AgSbF6 (2000 ppm) + TFA (2 equiv.) | 98% |