Table 3.

Effect of the temperature on the halogenation of 6 with catalyst K2.^a

Entry	Reagent	Solvent	T (°C)	t (h)	Product	ee (%)
1	F–TEDA	MeCN	0	0.3	6-F	86
2	F–TEDA	MeCN	rt	0.15	6-F	88
3	F–TEDA	MeCN	50	<0.3	6-F	79
4	NFSI	CH2Cl2	−25	–b	6-F	89b
5	NFSI	CH2Cl2	0	19	6-F	91
6	NFSI	CH2Cl2	rt	10	6-F	87.5
7	NCS	MeCN	rt	0.5	6-Cl	82
8	NCS	CH2Cl2	0	7	6-Cl	90

^aReactions were run to complete conversion (TLC), unless otherwise mentioned. ^bAnalysis at 15% conversion. Complete conversion occurred after warming to rt.