Dimethyl Sulfoxide → 1-(1,8-Diethyl-1,3,4,9-tetrahydropyrano[3,4-b]indol-1-yl)-propan-2-one

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Reaction Steps

To a solution of compound 12 (77 mg, 0.27 mmol), CH2Cl2 (2 mL), dry DMSO (76 μL, 1.07 mmol, 4.0 eq), and dry TEA (374 μL, 2.68 mmol, 10.0 eq) at room temperature under argon, sulfur trioxide-pyridine complex (Pyr-SO3, 171 mg, 1.07 mmol, 4.0 eq) was added in a portion-wise manner and stirred overnight. The resulting mixture was then diluted with brine and extracted three times with EtOAc. The combined organic phases were dried with Na2SO4, concentrated, and purified by column chromatography using 15:85:EtOAc:Hexane to give an off-white solid 39 mg, 51%): mp 154–155° C. 1HNMR (CDCl3, δ TMS): 0.80 (t, 3H), 1.37 (t, 3H), 2.02 (m, 2H), 2.21 (s, 3H), 2.78 (m, 2H), 2.88 (q, 2H), 3.14 (s, 2H), 3.98 (m 2H), 7.01–7.37 (m, 3H, Ar—H), 9.01 (br, 1H, NH). MS−: m/z 284 ([M−H]−). Anal. C18H23NO2): C, H, N.

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