Table 1.

Preliminary Experiments and Optimization ^a

entry	substrate	R1	ligand	product	yield (%)b
1	3	2-naphthyl	Xantphos	5	(20–66)
2	3	4-tolyl	Xantphos	6	(26)
3	3	2-naphthyl	Nixantphos	5	33 (41)
4	3	4-tolyl	Nixantphos	6	26 (53)
5	3	2-naphthyl	Dpe-phos	–	0
6	3	4-tolyl	Dpe-phos	–	0
7	4	2-naphthyl	Xantphos	7	(74)
8	4	4-tolyl	Xantphos	8	(65)
9	4	2-naphthyl	Nixantphos	7	57 (81)
10	4	4-tolyl	Nixantphos	8	73 (77)

^aConditions: 1.0 equiv of guanidine substrate, 1.5 equiv R–X, 2.4 equiv NaO^tBu, 2 mol % Pd₂(dba)₃, 8 mol % ligand, toluene (0.1 M), 107 °C. Reactions of 4 were quenched with an excess of aqueous HCl (1 M) to ensure complete protonation of the guanidine.

^bIsolated yields. Numbers in parentheses are NMR yields based on phenanthrene as an internal standard.