Table 1.

Optimization of the Fluorination Conditions^a

entry	solvent	reagenta	time [h]	yield [%]b [dr]c
1	CH3CN	Selectfluor	0.5	29 [57:43]
2	CH3CN	Py-F	24	26 [61:39]
3	CH3CN	NFSI	9.5	57 [89:11]
4	anhyd CH3CNd	NFSI	8	<10 [85:15]
5	2.0 equiv H2O in CH3CN	NFSI	8	43 [89:11]
6	1 % H2O in CH3CN	NFSI	12	62 [91:9]
7	2 % H2O in CH3CN	NFSI	12	68 [91:9]
8	5 % H2O in CH3CN	NFSI	31	29 [91:9]
9e	2 % H2O in CH CN	NFSI	6	22 [71:29]

^aIn all reactions, 1.1 equiv N-F reagent was added. Unless otherwise noted, reactions were run at 40 °C. DMP: Dess-Marin Periodinane; NSFI: N-fluoro-benzenesulfonimide; Py-F: N-fluoropyridinium triflate;

^bYields were determined by ¹HNMR analysis using mesitylene as the internal standard.

^cDiastereomeric ratios [dr] were determined using ¹H or/and ¹⁹F NMR spectroscopy.

^dCH₃CN distilled over CaH₂.

^eThe reaction temperature is 80 °C.