1,2-Dibromo-1,1,2,2-tetrafluoroethane → 2-(2-Bromo-thiophen-3-yl)-[1,3]dioxolane

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Reaction Conditions

Reaction Steps

A −78° C. solution of the dioxolane of Example 23(a) in dry THF (93 mL, Aldrich) was treated with n-butyllithium (34 mL, 50.7 mmol, 1.49 M/hexanes, Aldrich). The mixture was stirred at −78° C. for 35 minutes and then BrCF2CF2Br (6.1 mL, 51.1 mmol, Aldrich) was added. After 10 minutes, the mixture was allowed to warm to 0° C. and after 30 minutes at 0° C., the mixture was allowed to warm to room temperature. The solution was partitioned between H2O and ether (100 mL each). The layers were separated and the aqueous layer extracted with ether (100 mL). The combined ether solution was washed with 1 M sodium thiosulfate solution (2×100 mL) and brine (100 mL) and then was dried (MgSO4), filtered and evaporated to leave 11.15 g of 2-(2-Bromo-thiophen-3-yl)-[1,3]dioxolane as a yellow oil that was used directly in the next step.

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