General Approach to the Synthesis of Prochiral Atropisomeric Biaryls

Table 3

Optimisation of direct arylation reaction.

Entry	Base	Catalyst	Ligand	45 [%]	46 [%]	Conversion [%]
1	Cs2CO3	[RhCl(cod)]2	none	2	3	5
	Ag2CO3
2	Cs2CO3	[RhCl(cod)]2	none	32 (36)^b	2	34
3	Cs2CO3	[RhCl(cod)]2	PPh3	4^a	3^a	7^a
4	Cs2CO3	[RhCl(cod)]2	S-Phos	72 (64)^b	4	76
5	Cs2CO3	[RuCl2(p-cymene)]2	PPh3	1^a	1^a	2^a
6	Cs2CO3	[RuCl2(p-cymene)]2	tris(pentafluorophenyl)-phosphine	28	31	59
7	Cs2CO3	[RuCl2(p-cymene)]2	none	71	13	84
8	Cs2CO3	[RuCl2(p-cymene)]2	tris(2,4,6-trimethoxy-phenyl)phosphine	24	18	42
9	Cs2CO3	[RuCl2(p-cymene)]2	dppe	29	7	36
10	K2CO3	[RuCl2(p-cymene)]2	S-Phos	54	33	87

The reactions were carried out under argon atmosphere, in NMP, at 160°C, for 24 hours, HPLC yields, a2 equiv. of compound 44 were used in the reaction. bThe isolated yields are given in the parentheses.