. 2018 Dec 18;3(12):17617–17628. doi: 10.1021/acsomega.8b02147

Table 1. Optimization Studies^a.

				% yield^b
entry	base	solvent	time	3a^c	4a
1	KOAc	CH₃CN	4 d		75
2	K₂CO₃	CH₃CN	30 min	58
3	Cs₂CO₃	CH₃CN	30 min	27
4	NaOH	CH₃CN	25 min	62
5	Et₃N	CH₃CN	25 min	62
6	KOAc	THF	8 d		60
7	KOAc	MeOH	8 d		63
8	KOAc	toluene	8 d
9	KOAc	CH₃CN	4 d		78^d

Reaction scale: 1a (0.25 mmol, 1.0 equiv), 2a (0.25 mmol, 1.0 equiv), base (0.25 mmol, 1.0 equiv), and solvent (3 mL) at RT.

After silica gel column chromatography.

Slowly gets converted to 4a during purification and upon storage; prolonging the reaction time beyond the indicated time or heating to 60–80 °C in the case of entries 2–5 led to complex mixtures.

Acetic acid as the additive (1 mol %).

Table 1. Optimization Studiesa.

Table 1. Optimization Studies^a.