Table 5.

Optimization of the coupling reaction of 1c with D-alanine methyl ester (6b).^a

Entry	Pd catalyst (5 mol %)	Amino acid (ester) 6	Ln	Base	Time (h)	Yield (%)b
1	Pd2(dba)3	6a	L1	Cs2CO3	24	tracesc
2	Pd2(dba)3	6a	L2	Cs2CO3	24	0
3	Pd2(dba)3	6a	L3	Cs2CO3	24	0
4	Pd2(dba)3	6a	L4	Cs2CO3	24	0
5	Pd2(dba)3	6b	L1	Cs2CO3	1	93
6	Pd2(dba)3	6b	L1	K2CO3	3	85
7	Pd2(dba)3	6b	L1	NaOt-Bu	3	44
8	Pd2(dba)3	6b	L1	KOH	3	33
9	Pd2(dba)3	6b	L1	K3PO4	3	12
10	Pd2(dba)3	6b	L2	Cs2CO3	6	14
11	Pd2(dba)3	6b	L3	Cs2CO3	6	traces
12	Pd2(dba)3	6b	L4	Cs2CO3	24	0
13	Pd(OAc)2	6b	L1	Cs2CO3	24	20
14	Pd(OAc)2	6b	L1	K2CO3	24	15
15	Pd(OAc)2	6b	L1	NaOt-Bu	24	23
16	Pd(OAc)2	6b	L1	K3PO4	24	20
17	Pd(OAc)2	6b	L2	Cs2CO3	24	18
18	Pd(OAc)2	6b	L3	Cs2CO3	24	0
19	Pd(OAc)2	6b	L4	Cs2CO3	24	0

^aReaction conditions: N-methyl-4-bromo-7-azaindole (1c) (1.0 mmol), amino acid (ester) (1.2 mmol), base (3.0 mmol), palladium catalyst (5 mol %), ligand (10 mol %), and 2 mL of dioxane, 100 °C, 1–24 h. ^bYields reported are isolated yields. ^cTrace amount of product obtained by cross coupling of 1c with 6a.