Table 1.

Optimization of reaction conditions.^[a]

Entry	Solvent	Base/additive	3 a [%][b]	4 a [%][b]	Selectivity 3 a/4 a
1	DMAc	Cs2CO3	14	25	0.56
2	DMAc	K3PO4	27	31	0.87
3	DMAc	KOtBu	45	12	3.75
4	DMAc	NaOtBu	57	19	3.00
5	DMAc	NaH	58	–	–
6	DMAc/DMAc[c]	NaOMe	63/73	15/27	5.25/2.70
7	DMAc	K3PO4/TBACl	9	46	0.19
8	DMAc[c]	NaOMe/TBACl	7	93	0.08

[a] 1 equiv.=0.5 mmol, Atmospheric conditions unless otherwise noted. MAc=dimethylacetamide. [b] Isolated yield. [c] Argon atmosphere.