Table 1. Optimization of reaction conditions for cyclohexylation of p-toluidine with phenol ^a .

Entry	Catalyst	Solvent	T/°C	Yield b /%
1	Pd/C	Toluene	100	94
2	—	Toluene	100	n.r.
3	PdCl2	Toluene	100	n.r.
4	Pd(PPh3)4	Toluene	100	n.r.
5	Pd(dba)2	Toluene	100	34
6	Pd(PPh3)2Cl2	Toluene	100	n.r.
7	PdCl2(dtbpf)	Toluene	100	n.r.
8	Pd/C	THF	100	89
9	Pd/C	EtOH	100	47
10	Pd/C	Dioxane	100	86
11	Pd/C	H2O	100	80
12	Pd/C	MeCN	100	n.p.
13	Pd/C	DMF	100	n.r.
14	Pd/C	Toluene	120	86
15	Pd/C	Toluene	80	73
16 c	Pd/C	Toluene	100	95(92)
17 d	Pd/C	Toluene	100	83
18 e	Pd/C	Toluene	100	66

^aReaction conditions: phenol (0.2 mmol), p-toluidine (0.2 mmol), catalyst (10 mol%), sodium formate (6 equiv.) and solvent (0.8 mL) under an argon atmosphere.

^bYields were determined by GC analysis with mesitylene as internal standard; isolated yields in brackets.

^cPd/C (7 mol%) was used.

^dPd/C (5 mol%) was used.

^eH₂ (1 atm) was used instead of sodium formate.