Table 1. Summary of end-capping procedure optimization.
| Entry | PFB-MgCl a (eq.) | Temperature | 2 minutes
b
|
70 minutes
b
|
||||
| Mono-PFB | Di-PFB | PFBP? | Mono-PFB | Di-PFB | PFBP? | |||
| 1 | 0.3 | RT | 64% | 3% | Yes | 37% | 30% | Yes |
| 2 | 0.3 | 0 °C | 64% | 0% | No | 66% | 4% | No |
| 3 | 0.1 | 0 °C | 49% | 0% | No | 65% | 6% | No |
aA 0.5 M solution of pentafluorophenylmagnesium chloride (PFB-MgCl) freshly prepared from iodopentafluorobenzene and n-butylmagnesium chloride at –78 °C.
bApproximate composition based on matrix-assisted laser desorption–ionization time-of-flight (MALDI-TOF) peak intensities.