N-bromobutanimide → (5r)-2-Bromo-4-[(4-methoxyphenyl)sulfonyl]-5-methyl-4,5-dihydrothieno[3,2-c]isoquinoline

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A solution of (5R)4-[(4-methoxyphenyl)sulfonyl]-5-methyl-4,5-dihydrothieno[3,2-c]isoquinoline (12.7 g, 34 mmol) in 1:1 acetic acid-chloroform (300 mL) was treated with N-bromosuccinimide (6.1 g, 34 mmol) at −10° C. After ca. 5 min., the cooling bath was removed and the mixture was warmed to 23° C. After 18 h the resulting solution was poured into water (1.2 L) and extracted with methylene chloride (4×400 mL). The organic solution was washed with 25% aqueous potassium hydroxide and brine (1 L each), dried (K2CO3), and concentrated in vacuo to give the crude product (15.5 g) as a green solid which was loaded onto a column of silica gel (100 g) in warm 25% methylene chloride-hexane. Flash chromatography eluting 25-, then 50-, and then 75% methylene chloride-hexane gave the title compound (15.1 g, 98%, m.p. 136-38° C.) as a white solid. [α]D=+219.4. 1H NMR (400 MHz) δ 1.21 (d, J=7 Hz, CHCH3), 3.64 (s, 3H, OCH3), 5.40 (m, 1H, CHCH3), 6.69 (d, J=9 Hz, 2H, ArH), 6.98 (d, J=7.5 Hz, 1H, ArH), 7.08 (m, 1H, ArH), 7.14 (m, 1H, ArH), 7.16-7.23 (overlapping m, 3H, ArH), 7.36 (s, 1H, ArH). MS (ESI) m/z 450 [M+H]+ Analysis calc. for C19H16BrNO3S2: C, 50.67: H, 3.58; N, 3.11. Found: C, 50.68; H, 3.37; N, 3.04

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