5-Bromo-1-benzothiophene → 4-(5-Bromobenzo[b]thiophen-2-yl)-2-methyl-1,2,3,4-tetrahydroisoquinoline-4-ol

HRID 1983901Notes

Reaction equation

HRID 1983901 reaction equation
[Br:1][C:2]1[CH:3]=[CH:4][C:5]2[S:9][CH:8]=[CH:7][C:6]=2[CH:10]=1.C([Li])(C)(C)C.[CH3:16][N:17]1[CH2:26][C:25](=[O:27])[C:24]2[C:19](=[CH:20][CH:21]=[CH:22][CH:23]=2)[CH2:18]1>>[Br:1][C:2]1[CH:3]=[CH:4][C:5]2[S:9][C:8]([C:25]3([OH:27])[C:24]4[C:19](=[CH:20][CH:21]=[CH:22][CH:23]=4)[CH2:18][N:17]([CH3:16])[CH2:26]3)=[CH:7][C:6]=2[CH:10]=1

Participants

4

Reactant 3

HCID 27765785-Bromo-1-benzothiopheneHCID 106308122-Methyl-2,3-dihydroisoquinolin-4(1H)-oneHCID 178418306HCID 178418306, compound

Product 1

HCID 689934704-(5-Bromobenzo[b]thiophen-2-yl)-2-methyl-1,2,3,4-tetrahydroisoquinoline-4-olYield 8%

Conditions

Temperature
-75 °C

Procedure

To a solution of 5-bromobenzothiophene (511 mg, 2.4 mmol) at −75° C., was added t-butyllithium (1.7 M in pentane, 1.6 mL, 2.6 mmol) dropwise. The reaction mixture was stirred at −75° C. for 1 hour. To the resulting dark brown mixture was added 2-methyl-2,3-dihydro-1H-isoquinolin-4-one (323 mg, 2.0 mmol), which was prepared using the method described by Hanna et al., J. Med. Chem., 17(9):1020-1023 (1974), which is hereby incorporated by reference in its entirety. The reaction mixture was stirred for 15 hours with gradual warming up. The mixture was quenched with saturated ammonium chloride and extracted with ethyl acetate (3×50 ml). The combined organic extracts were washed with saturated sodium chloride, dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo. Purification by medium pressure silica gel chromatography (10-40% ethyl acetate/hexanes) followed by preparative HPLC afforded 4-(benzo[b]thiophen-5-yl)-2-methyl-1,2,3,4-tetrahdro-isoquinoline-4-ol (65 mg, 11%) and 4-(5-bromobenzo[b]thiophen-2-yl)-2-methyl-1,2,3,4-tetrahydroisoquinoline-4-ol (58 mg, 8%). 4-(Benzothiophen-5-yl)-2-methyl-1,2,3,4-tetrahydroisoquinoline-4-ol: 1H NMR (CDCl3, 500 MHz) δ 7.81 (d, J=8.5 Hz, 1H), 7.69 (d, J=8.5 Hz, 1H), 7.34-7.23 (m, 4H), 7.20 (s, 1H), 7.18 (d, J=7.3 Hz, 1H), 7.10 (d, J=7.6 Hz, 1H), 3.91 (s, 1H), 3.84 (d, J=15.0 Hz, 1H), 3.53 (d, J=15.0 Hz, 1H), 3.11 (dd, J=11.6, 1.4 Hz, 1 H), 2.87 (d, J=11.6 Hz, 1H), 2.50 (s, 3H); ESI MS m/z=296 [M+H]+. 4-(5-Bromobenzothiophen-2-yl)-2-methyl-1,2,3,4-tetrahydroisoquinoline-4-ol: 1H NMR (CDCl3, 300 MHz) δ 7.81 (d, J=1.8 Hz, 1H), 7.66 (d, J=8.5 Hz, 1H), 7.38 (dd, J=8.5, 1.9 Hz, 1H), 7.30-7.23 (m, 2H), 7.18 (d, J=7.3 Hz, 1H), 7.11 (s, 1H), 7.07 (d, J=7.6 Hz, 1H), 3.69 (d, J=15.0 Hz, 1H), 3.48 (d, J=15.0 Hz, 1H), 3.10 (dd, J=11.6, 1.3 Hz, 1H), 2.83 (d, J=11.6 Hz, 1H), 2.47 (s, 3H); ESI MS m/z=374 [M+H]+.

Workup

  1. customwas prepared
  2. stirringThe reaction mixture was stirred for 15 hours
  3. temperaturewith gradual warming up
  4. customThe mixture was quenched with saturated ammonium chloride
  5. extractionextracted with ethyl acetate (3×50 ml)
  6. washThe combined organic extracts were washed with saturated sodium chloride
  7. dry with materialdried over anhydrous sodium sulfate
  8. filtrationfiltered
  9. concentrationconcentrated in vacuo
  10. customPurification by medium pressure silica gel chromatography (10-40% ethyl acetate/hexanes)

Sources & evidence

ORD record
ord-da5621f9fad8401ebe10bc9b7f8a4d09
Source dataset
uspto-grants-2009_06
Patent number
US07541357B2

Reaction notes

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