TABLE 1.

Screening of olefination conditions

entry	basea	solvent	Additive	T (°C); time	(%) E/Z;b yield (%)c
1d	KHMDS	THF	--	−55; 10 min	82/18; 86
2d	LHMDS	THF	--	−78; 10 min	88/12; 97
3d	LHMDS	THF	MgBr2Et2Oe	rt; 4 h	89/11; 78
4d	LHMDS	DMF	DMPUf	−78; 10 min	63/37; 74
5d	LHMDS	DMPU	--	0; 10 min	58/42; NAg
6h	DBU	CH2Cl2	--	rt; 10 min	69/31; 91
7h	DBU	CH2Cl2	--	0; 10 min	70/30; 92
8h	DBU	CH2Cl2	--	−55; 10 min	74/26; 95
9h	DBU	CH2Cl2	--	−78; 10 min	74/26; NAg
10h	DBU	CH2Cl2	MgBr2Et2Oe	rt; 30 h	60/40; Inci
11h	DBU	THF	MgBr2Et2Oe	rt; 30 h	90/10; Inci
12h	Cs2CO3	CH2Cl2	--	rt; 6 h	74/26; NAg

^aKHMDS and LHMDS: 2.4 molar equiv. DBU: 4.0 molar equiv. Cs₂CO₃: 3.0 molar equiv.

^bE/Z ratio of diastereomers in the crude reaction mixture was determined by ¹⁹F NMR, prior to isolation.

^cYields are of isolated and purified products.

^dSulfone 3, 2.0 molar equiv.

^e3.0 molar equiv.

^fCosolvent, ratio of DMF/DMPU 1:1 (v/v).

^gProducts were not isolated.

^hSulfone 3, 2.5 molar equiv.

ⁱReaction was incomplete after 30 h.