Table 1. Optimization of reaction conditions ^a .

Entry	L	Base	Yield b (%)
1	dmpe	K3PO4	51
2	dmpe	KOtBu	84
3	dmpe	NaOtBu	80
4	dmpe	CsOH	82
5	dmpe	KOH	78
6	dmpe	Et3N	0
7	dmpe	K2CO3	4
8	dmpe	—	0
9	—	KOtBu	0
10 c	dmpe	KOtBu	0
11	dppb	KOtBu	11
12	dppp	KOtBu	15
13	dppm	KOtBu	4
14	P(p-Tolyl)3	KOtBu	4

^a 1a (0.28 mmol, 1.4 equiv.), N₂H₄·H₂O (0.3 mmol, 1.5 equiv.), THF (0.14 mL), rt, 30 min; 2a (0.20 mmol, 1.0 equiv.), [Ru(p-cymene)Cl₂]₂ (0.003 mmol, 1.5 mol%), ligand (0.006 mmol, 3.0 mol%), base (0.1 mmol, 50 mol%), additive: CsF (0.15 mmol, 75 mol%), 45 °C, 12 h, under N₂.

^bYields were determined by crude ¹H NMR using mesitylene as an internal standard.

^cWithout [Ru(p-cymene)Cl₂]₂.