Table 1.
Screening of reaction conditionsa
| |||
|---|---|---|---|
| Entry | Base (molar equiv) | Solvent | Yield (%) |
| 1 | NEt3 (10) | CH2Cl2 | NRb |
| 2 | K2CO3 (10) | Acetone | NRb |
| 3 | K2CO3 (10) | THF-H2O | 23c |
| 4 | Cs2CO3 (10) | CH2Cl2 | 57d |
| 5 | Cs2CO3 (2) | CH2Cl2 | 49d |
| 6 | TMGe (10) | CH2Cl2 | 25d |
| 7 | DBUe (10) | CH2Cl2 | 67d |
| 8 | DBU (3) | CH2Cl2 | 62d |
| 9 | DBU (10) | THF | 68d |
| 10 | Cs2CO3 (10) | THF | 67d |
| 11 | Cs2CO3 (2) | THF | 71d |
a
For synthesis of 2a, 1a, and the sulfide precursor, see the Supporting Information.
b
No reaction.
c
Not isolated, conversion determined by 19F NMR.
d
Isolated yield.
e
TMG: 1,1,3,3-tetramethylguanidine; DBU: 1,8-diazabicyclo[5.4.0]undec-7-ene.