Optimization for the δ-carbon Michael addition/isomerization reaction^a.

Entry	Solvent	Additive	R	Yieldb [%]	eec [%]
1	Toluene	No	CHPh2	90	71
2	Toluene	Phenol	CHPh2	86	80
3	Toluene	p-OMePhOH	CHPh2	87	81
4	Toluene	o-OMePhOH	CHPh2	87	83
5	Toluene	PhCO2H	CHPh2	73	79
6	Mesitylene	o-OMePhOH	CHPh2	88	82
7	MTBE	o-OMePhOH	CHPh2	71	81
8	PhCl	o-OMePhOH	CHPh2	86	80
9	Dioxane	o-OMePhOH	CHPh2	82	82
10	Toluene	o-OMePhOH	Me	86	87
11	Toluene	o-OMePhOH	Ph	82	88
12	Toluene	o-OMePhOH	Bn	83	85
13	Toluene	o-OMePhOH	t Bu	76	77
14d	Toluene	o-OMePhOH	Ph	80	93

^aReactions were performed with 4b (0.1 mmol), 2′ (0.15 mmol), the additive (0.05 mmol) and NUSIOC-Phos (0.01 mmol) in the solvent specified (1.0 mL) at 25 °C for 24 h.

^bIsolated yield.

^cDetermined by HPLC analysis on a chiral stationary phase.

^dThe reaction mixture was first stirred at 0 °C for 6 h and then at 25 °C for 24 h.