Nature Communications

Table 1 Optimization of the reaction conditions^a.

From: C(sp³)−C(sp³) bond formation via nickel-catalyzed deoxygenative homo-coupling of aldehydes/ketones mediated by hydrazine


Entry	Catalyst	Ligand	Base	Solvent	3a yield(%)^b
1	NiCl₂	PMe₃	DBU	THF	25
2	NiBr₂	PMe₃	DBU	THF	22
3	Ni(acac)₂∙4H₂O	PMe₃	DBU	THF	7
4	Ni(OAc)₂	PMe₃	DBU	THF	18
5	NiCl₂(PPh₃)₂	PMe₃	DBU	THF	12
6	Ni(cod)₂	PMe₃	DBU	THF	20
7	--	PMe₃	DBU	THF	n.p.
8	NiCl₂	--	DBU	THF	n.p.
9	NiCl₂	PMe₃	--	THF	n.p.
10	NiCl₂	PMe₃	DABCO	THF	14
11	NiCl₂	PMe₃	Et₃N	THF	3
12	NiCl₂	PMe₃	KOH	THF	n.p.
13	NiCl₂	PMe₃	t-BuOK	THF	10
14	NiCl₂	dppb	DBU	THF	28
15	NiCl₂	dppe	DBU	THF	32
16	NiCl₂	dppp	DBU	THF	45
17	NiCl₂	dppf	DBU	THF	21
18	NiCl₂	2,2'-bipyridine	DBU	THF	40
19	NiCl₂	1,10-phenanthroline	DBU	THF	42
20	NiCl₂	IPr∙HCl	DBU	THF	55
21	NiCl₂	SIPr∙HCl	DBU	THF	49
22	NiCl₂	IMes∙HCl	DBU	THF	61
23	NiCl₂	SIMes∙HCl	DBU	THF	54
24	NiCl₂	IMes∙HCl	DBU	1,4-dioxane	65
25^c	NiCl₂	IMes∙HCl	DBU	1,4-dioxane	86 (83)
26^{c, d}	NiCl₂	IMes∙HCl	DBU	1,4-dioxane	55
27 ^{c, e}	NiCl₂	IMes∙HCl	DBU	1,4-dioxane	71

^aGeneral conditions: 2a (2 × 0.1 mmol), catalyst (0.02 mmol, 20 mol%), ligand (monodentate phosphine ligand PMe₃ 40 mol %, other ligands 20 mol %), base (0.22 mmol, 2.2 equiv.) and solvent (1.0 mL) at 100 °C for 24 h under an argon atmosphere.
^bYields were determined by ¹H NMR with dibromomethane as internal standard; isolated yields in parentheses.
^cNiCl₂ (0.03 mmol, 30 mol%), IMes∙HCl (0.03 mmol, 30 mol%).
^d80 °C.
^e120 °C.

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