Table 1.

Optimization of the Palladium-Catalyzed Carbonylative Cyclization of Methyl 2-Iodobenzoate and Benzylamine, Using Various Phosphine Ligands (eq 1)^a

entry	ligand (20 mol %)	% isolated yield
1	PPh3	76
2	P(o-tolyl)3	14
3	tri(2-methoxyphenyl)phosphine	38
4	tricyclohexylphosphine	82
5	triethylphosphine	39
6	tri(2-furyl)phosphine	66
7	diphenyl-2-pyridylphosphine	84
8	(2-biphenyl)di-tert-butylphosphine	31
9	tri-tert-butylphosphine	53
10	2-dicyclohexylphosphino-2′,6′-  dimethoxybiphenyl (S-PHOS)	66
11	2-dicyclohexylphosphino-2′-  (N,N-dimethylamino)biphenyl (DavePhos)	64
12	(±)-2,2′-bis(diphenylphosphino)-1,  1′-binaphthalene (BINAP)	19
13	2,2′-bis(di-p-tolylphosphino)-1,  1′-binaphthalene (Tol-BINAP)	71
14	4,5-bis(diphenylphosphino)-9,  9-dimethylxanthene (Xantphos)	78
15	1,1′-bis(diphenylphosphino)  ferrocene (dppf)	17
16	1,1-bis(diphenylphosphino)  methane (dppm)	34
17	1,2-bis(diphenylphosphino)  ethane (dppe)	~5
18	1,3-bis(diphenylphosphino)  propane (dppp)	91
19	1,4-bis(diphenylphosphino)  butane	81
20	1,5-bis(diphenylphosphino)  pentane	64

^aRepresentative procedure: methyl 2-iodobenzoate (0.5 mmol), benzylamine (1.2 equiv), Pd(OAc)₂ (10 mol %), ligand (20 mol %), Cs₂CO₃ (2 equiv), and toluene (6 mL) were placed in a 4 dram vial. The vial was sealed and flushed with CO. The reaction was then stirred at 95 °C for 24 h with a CO balloon on top of the vial.