Table 1.

Optimization of the reaction conditions

Entry	Rh catalysta	Base	Solvent	Temp.	Yield	ee
1	Rh2(S-DOSP)4 (1 mol %)	DIPEA	TFT	25°C	58%	59%
2	Rh2(S-PTTL)4 (1 mol %)	DIPEA	TFT	25°C	66%	87%
3	Rh2(S-PTAD)4 (1 mol %)	DIPEA	TFT	25°C	61%	91%
4	Rh2(S-BTPCP)4 (1 mol %)	DIPEA	TFT	25°C	N.D.	–
5	Rh2(S-PTAD)4 (1 mol %)	K2CO3	TFT	25°C	N.R.	–
6	Rh2(S-PTAD)4 (1 mol %)	CsCO3	TFT	25°C	N.R.	–
7	Rh2(S-PTAD)4 (1 mol %)	tBuOK	TFT	25°C	N.R.	–
8	Rh2(S-PTAD)4 (1 mol %)	DIPEA	Toluene	25°C	53%	82%
9	Rh2(S-PTAD)4 (1 mol %)	DIPEA	DCM	25°C	47%	20%
10	Rh2(S-PTAD)4 (1 mol %)	DIPEA	DMF	25°C	Trace	–
11	Rh2(S-PTAD)4 (1 mol %)	DIPEA	TFT	40°C	73%	87%
12	Rh2(S-PTAD)4 (1 mol %)	DIPEA	TFT	0°C	21%	–
13	Rh2(S-PTAD)4 (0.5 mol %)	DIPEA	TFT	25°C	61%	92%
14	Rh2(S-PTAD)4 (0.25 mol %)	DIPEA	TFT	25°C	50%	74%
15b	Rh2(S-PTAD)4 (0.5 mol %)	DIPEA	TFT	25°C	93%	95%

N.D., Not detect.

^aReaction conditions: N-Triftosylhydrazone 1 (0.2 mmol), 1,1-diphenylethylene 2 (0.1 mmol), [Rh] catalyst (1 mol %), DIPEA (N, N-diisopropylethylamine) (0.2 mmol), TFT (benzotrifluoride, 3.0 mL), 12 h, under N₂.

^bα-Methyl-4-NO₂-phenylethylene was used.