Table 1.

Optimization of reaction conditions for asymmetric Büchner reaction of N-propargyl ynamide 1a

Entry	L	Reaction conditions	Yield (%)a	Ee (%)b
1	L1	DCM, 35 °C, 0.5 h	86	49
2	L2	DCM, 35 °C, 0.5 h	83	55
3	L3	DCM, 35 °C, 0.5 h	71	<5
4	L4	DCM, 35 °C, 0.5 h	79	11
5	L5	DCM, 35 °C, 0.5 h	90	42
6	L6	DCM, 35 °C, 0.5 h	94	79
7	L7	DCM, 35 °C, 0.5 h	93	41
8	L8	DCM, 35 °C, 0.5 h	86	51
9	L9	DCM, 35 °C, 0.5 h	95	81
10	L9	DCE, 35 °C, 0.5 h	94	84
11	L9	toluene, 35 °C, 0.5 h	94	85
12	L9	THF, 35 °C, 0.5 h	95	70
13	L9	toluene, 0 °C, 8 h	93	87
14	L9	toluene, −20 °C, 40 h	95	96

Reaction conditions: 1a (0.05 mmol), Cu(MeCN)₄PF₆ (0.005 mmol), L (0.006 mmol), NaBAr^F₄ (0.006 mmol), solvent (1 mL), in Schlenk tubes.

^aMeasured by ¹H NMR using diethyl phthalate as internal standard.

^bDetermined by HPLC analysis. Ms = methanesulfonyl, Mes = mesityl, NaBAr^F₄ = sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, DCM = dichloromethane, DCE = 1,2-dichloroethane, THF = tetrahydrofuran.