Table 1. Optimization of Reaction Conditionsa.
| entry | equiv of 1a | PC | DABCO (equiv) | base (equiv) | H2O (equiv) | yield (%) |
|---|---|---|---|---|---|---|
| 1 | 1.5 | fac-Ir(ppy)3 (1%)b | Na2CO3 (1.5) | 20 | 54 | |
| 2 | 1.5 | fac-Ir(ppy)3 (1%)b | 1 | Na2CO3 (1.5) | 20 | traces |
| 3 | 3 | fac-Ir(ppy)3 (1%)b | 1 | Na2CO3 (3) | 20 | 97 |
| 4 | 1.5 | fac-Ir(ppy)3 (1%)b | 0.5 | Na2CO3 (1.5) | 20 | 96 |
| 5 | 1.5 | Ru(bpy)3(PF6)2 (1%)b | 0.5 | Na2CO3 (1.5) | 20 | tracesc |
| 6 | 1.5 | Ru(bpy)3·6H2Ob (1%) | 0.5 | Na2CO3 (1.5) | 20 | tracesc |
| 7 | 1.5 | Ru(bpy)3PF6 (1%)b | Na2CO3 (1.5) | 20 | tracesc | |
| 8 | 1.5 | eosin Y (5%)d | 0.5 | Na2CO3 (1.5) | 20 | ND |
| 9 | 1.5 | eosin Y (5%)d | Na2CO3 (1.5) | 20 | ND | |
| 10 | 1.5 | rose bengal (1%)e,f | ND | |||
| 11 | 1 | fac-Ir(ppy)3 (1%)b | 0.33 | Na2CO3 (1) | 20 | 55c |
| 12 | 1 | fac-Ir(ppy)3 (1%)b | 0.33 | Na2CO3 (1) | MeCN/H2O 1:1 | 73c |
| 13 | 1.5 | fac-Ir(ppy)3 (1%)b | 0.5 | Na2CO3 (1.5) | MeCN/H2O 1:1 | 84c |
| 14 | 1.5 | fac-Ir(ppy)3 (1%)b | 0.5 | Na2CO3 (1.5) | MeCN/H2O 1:3 | 78c |
| 15 | 1.5 | fac-Ir(ppy)3 (1%)b | 0.5 | Na2CO3 (1.5) | 100% | 62 |
| 16 | 1.5 | fac-Ir(ppy)3 (1%)b | 0.5 | Na2CO3 (1.5) | ND | |
| 17 | 1.5 | fac-Ir(ppy)3 (1%)f | 0.5 | Na2CO3 (1.5) | 20 | 98% |
| 18 | 1.5 | fac-Ir(ppy)3 (1%)g | 0.5 | Na2CO3 (1.5) | 20 | ND |
| 19 | 1.5 | fac-Ir(ppy)3 (1%)h | 0.5 | Na2CO3 (1.5) | 20 | ND |
| 20 | 1.5 | fac-Ir(ppy)3 (1%) | 0.5 | 20 | 25% | |
| 21 | 1.5 | fac-Ir(ppy)3 (1%) | 0.5 | Na2HPO4 (1.5) | 20 | 96% |
| 22 | 1.5 | fac-Ir(ppy)3 (1%) | 0.5 | Na2HPO4 (1.5) | 20 | 46% |
| 23 | 1.5 | 0.5 | Na2CO3 (1.5) | 20 | ND |
a
Compound 2 0.25 mmol in MeCN 0.1 M.
b
Degassing by freeze–pump–thaw.
c
Yield by 1H NMR.
d
Green LED 16 W.
e
EtOAc as the solvent.
f
No degassing under an Ar atmosphere.
g
Open flask.
h
Under a O2 atmosphere.