Triethylamine → (R)-5,7-difluoro-1,2,3,4-tetrahydronaphthalen-2-yl methanesulfonate

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Reaction Steps

A mixture of (R)-5,7-difluoro-1,2,3,4-tetrahydro-2-hydroxynaphthalene (59.0 g, 0.32 mol), prepared as in Example 3, and triethylamine (13.8M, 74.2 mL, 0.53 mol) in 1.78 L of diethyl ether was cooled using a methanol/ice bath. Methanesulfonyl chloride (12.9M, 37.2 mL, 0.48 mol) was added under argon over 5-10 minutes and the mixture was stirred at room temperature for 18 hours. The mixture was partitioned between water and ether and the ether layer was separated and the aqueous layer was extracted with ether. The combined ether layers were washed once with each of 1N hydrochloric acid, saturated sodium bicarbonate solution and brine and then dried over magnesium sulfate. Evaporation gave crude (R)-5,7-difluoro-1,2,3,4-tetrahydronaphthalen-2-yl methanesulfonate as an off-white solid (87.12 g), m.p. 79°-80° C. [α]D25 =+16.77° (c=2.0, CHCl3).

Provenance & Evidence