(Diethylamino)sulfur trifluoride → 1,8-Diethyl-1-(2-fluoroethyl)-1,3,4,9-tetrahydropyrano[3,4-b]indole

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Reaction Steps

To a stirred solution of compound 1 (136 mg, 0.5 mmol) in CH2Cl2 (2 mL) at −40° C. under argon, DAST (396 μL, 3.0 mmol, 6.0 eq) was slowly added in a dropwise manner. The resulting mixture was allowed to warm to room temperature and stirred for one hour before being cooled to 0° C. and quenched with MeOH (1 mL). The mixture was stirred an additional thirty minutes at room temperature, and then saturated NaHCO3 (10 mL) was added dropwise. The resulting aqueous layer was extracted three times with CH2Cl2. The combined organic phases were dried with Na2SO4, concentrated, and purified by column chromatography using 5:95:EtOAc:Hexane to give a yellow-white solid (45 mg, 33%): mp 118–119° C. 1HNMR (CDCl3, δ TMS): 0.88 (t, 3H), 1.37 (t, 3H), 1.94 (m, 2H), 2.29 (m, 2H), 2.78 (m, 2H), 2.86 (q, 2H), 3.99 (m, 2H), 4.57 (qq, 2H), 7.03–7.38 (m, 3H, Ar—H), 7.65 (br, 1H, NH). MS−: m/z 310 (MCl−), 274 ([M−H]−). Anal. (C17H22NOF): C, H, N.

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