Table 1.

PFEx catalyst screen.

Entry	Catalyst	pKaH (MeCN)	Time (h)	Conversion (%)a
1	P4-tBu	42.7	1	>99
2	P2-tBu	33.5	1.5	>99
3	TBD	26.2	5	>99
4	BTMG	~26	14	91
5	DBU	24.3	14	80
6	P1-tBu	26.9	14	10
7	TMG	23.7	14	9
8	DPG	18.8	14	Trace
9	BEMP	27.5	14	66
10	MTBD	25.0	14	64
11	DMAP	18.0	14	0
12 b	TBD	26.2	2	>99
13c	TBD	26.2	7	16
14d	TBD	26.2	7	20

Reactions were conducted on a 0.10 mmol scale in acetonitrile (0.25 M). Refer to supplementary information Figure S4 for a list of catalyst structures.

^[a]Conversions were determined by ³¹P NMR and ¹⁹F NMR.

^[b]1.20 equiv HMDS and 3, 5-dimethyphenol in MeCN (0.5 M) were employed.

^[c]HMDS was replaced with Et₃N (1.0 equiv).

^[d]Without HMDS.