Optimization of the reaction conditions^a.

Entry	Cat.	Hydrogen source	Yield (%)	ee (%)
1	(S,S)-1a	HCOONa (5 equiv.)	41	93
2	(S,S)-1b	HCOONa (5 equiv.)	<5	—
3	(S,S)-1c	HCOONa (5 equiv.)	80	87
4	(S,S)-1d	HCOONa (5 equiv.)	83	96
5	(S,S)-1e	HCOONa (5 equiv.)	78	79
6	(S,S)-1f	HCOONa (5 equiv.)	79	94
7	(S,S)-1g	HCOONa (5 equiv.)	84	94
8	(S,S)-1h	HCOONa (5 equiv.)	95	97
9b	(S,S)-1h	HCOONa (5 equiv.)	24	95
10c	(S,S)-1h	HCOOH/NEt3 (5:2)	0	—
11c	(S,S)-1h	HCOOH/NEt3 (1.1:1)	46	95

^aReaction conditions: phenylacetylene (2a; 5 mmol), CF₃SO₃H (20 mol%), H₂O (2 equiv.), CF₃CH₂OH (2 mL), 40 °C, 6 h; then 0.5 mol% catalyst, hydrogen source (5 equiv.), and H₂O (2 mL) were added, 50 °C, 24 h. The yield was determined by GC with an internal standard (mesitylene). The ee values were determined by HPLC analysis.

^bHexafluoro-2-propanol (HFIP) was used as a solvent.

^c0.5 mL of HCOOH/NEt₃ mixture was used, the data in the brackets are molar ratio.