Nature Communications

Table 1 Optimization of reaction conditions^a

From: Asymmetric synthesis of β-amino acid derivatives by stereocontrolled C(sp³)-C(sp²) cross-electrophile coupling via radical 1,2-nitrogen migration


Entry	[Ni]/reductant	Ligand	CPA	Yield of 3 (%)^b	Yield 3’(%)^b	er of 3^c
1	NiBr_2•dme/Zn	L1	–	17	61	–
2	NiBr_2•dme /Mn	L1	–	<10	21	–
3	NiBr_2•dme /B₂neo₂	L1	–	79(74)	Trace	–
4	NiBr_2•dme /B₂pin₂	L1	–	<10	Trace	–
5	NiBr_2•dme/B₂cat₂	L1	–	<10	Trace	–
6	NiBr_2•dme/B₂neo₂	L2	–	70	Trace	–
7	NiBr_2•dme/B₂neo₂	L3	–	74	Trace	–
8	NiBr_2•dme/B₂neo₂	L4	–	64	Trace	–
9	NiBr_2•dme/B₂neo₂	L5	–	61	Trace	–
10	NiBr_2•dme/B₂neo₂	L6	–	57	Trace	–
11^d	NiBr_2•dme/B₂neo₂	(S,S)-L7	–	62	Trace	83:17
12^d	NiBr_2•dme/B₂neo₂	(S,S)-L8	–	<10	Trace	n.d.
13^d	NiBr_2•dme/B₂neo₂	(S,S)-L9	–	50	Trace	74:26
14^d	NiBr_2•dme/B₂neo₂	(S,S)-L10	–	64	Trace	85:15
15^d	NiBr_2•dme/B₂neo₂	(S,S)-L11	–	47	Trace	81:19
16^d	NiBr_2•dme/B₂neo₂	(S,S)-L10	(R)-CPA 1	62	Trace	90:10
17^d	NiBr_2•dme/B₂neo₂	(S,S)-L10	(R)-CPA 2	63(60)	Trace	97:3
18^d	NiBr_2•dme/B₂neo₂	(S,S)-L10	(S)-CPA 1	59	Trace	74:26
19^d	NiBr_2•dme/B₂neo₂	(S,S)-L10	(R)-CPA 3	57	Trace	89:11
20^d	NiCl_2•dme/B₂neo₂	(S,S)-L10	(R)-CPA 2	56	Trace	90:10

^a Standard conditions: 1a (0.2 mmol.), 2a (2 euqiv.), NiBr₂•dme (10 mol%), Ligand (12 mol%), B₂neo₂ (2 equiv), H₂O (2 equiv) K₂CO₃ (2 equiv), and CH₃CN/EtOH (v: v = 1.8: 0.2, 0.1 M) at 50 °C under argon atmosphere for 30 h. B₂neo₂ bis(neopentyl glycolato)diboron, NMP N-methylpyrrolidone, DMA dimethyl acetamide, CPA chiral phosphoric acid, cat catecholato; pin pinacolato. n.d. not detected.
^b Yields were determined by gas chromatography (GC) using n-dodecane as an internal standard; isolated yields are reported in parentheses.
^c Enantiomeric ratios (e.r.) were determined using chiral HLPC.
^d Na₂CO₃ instead of K₂CO₃, on a 0.1 mmol scale at 40 °C for 36 h.

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