Table 4. Reaction of halo-tryptophans with commercially-available alkynes 27–33 ^a .

Entry	Tryptophan	Alkyne	Product	Conversion b (yield c )/%
1	5-Br 18	27	45	>99 (81)
2	6-Br 21	27	46	>99
3	7-Br 22	27	47	81
4	7-I 23	27	47	85
5	5-Br 18	28	48	63 (26)
6	6-Br 21	28	49	>99
7	7-Br 22	28	50	74
8	7-I 23	28	50	39
9	5-Br 18	29	51	54 (51)
10	6-Br 21	29	52	>99
11	7-Br 22	29	53	>99
12	7-I 23	29	53	56
13	5-Br 18	30	54	16
14	5-Br 18	30	54	50 (∼25 d )
15	5-Br 18	31	55	<1
16	5-Br 18	32	56	<1
17	5-Br 18	33	57	<1

^aSubstrate (0.1 mmol, 1.0 eq.), alkyne (0.3 mmol, 3.0 eq.), PdCl₂(CH₃CN)₂ (5 mol%), sXPhos (15 mol%), Cs₂CO₃ (2.5 eq.), water/acetonitrile (1 : 1, 2 mL, degassed), microwave heating, 100 °C, 2 h.

^bBased on NMR ratios of starting material to product in CD₃OD.

^cAverage of three isolated yields.

^dProduct co-eluted with sXPhos 4 and could not be isolated pure, the approximate yield is based on a single isolation.