Dichloromethane → alpha-Dihydrotetrabenazine

HRID 599190

Reaction equation

HRID 599190 reaction equation
[CH3:1][CH:2]([CH2:4][C@H:5]1[C:18](=[O:19])[CH2:17][C@H:16]2[N:7]([CH2:8][CH2:9][C:10]3[C:15]2=[CH:14][C:13]([O:20][CH3:21])=[C:12]([O:22][CH3:23])[CH:11]=3)[CH2:6]1)[CH3:3].[BH4-].[Na+].C(Cl)Cl>C(O)C>[CH3:3][CH:2]([CH2:4][C@H:5]1[C@H:18]([OH:19])[CH2:17][C@H:16]2[N:7]([CH2:8][CH2:9][C:10]3[C:15]2=[CH:14][C:13]([O:20][CH3:21])=[C:12]([O:22][CH3:23])[CH:11]=3)[CH2:6]1)[CH3:1]

Participants

5

Reactant 3

HCID 6344DichloromethaneHCID 667453(3R,11bR)-1,3,4,6,7,11b-Hexahydro-9,10-dimethoxy-3-(2-methylpropyl)-2H-benzo(a)quinolizin-2-oneHCID 4311764Sodium borohydride

Product 1

HCID 14580381alpha-Dihydrotetrabenazine

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

To a 0.11 M solution of (+)-TBZ (15) in ethanol at 0° C. was added NaBH4 (2.85 eq). The reaction mixture was allowed to stir for 60 min. at room temperature. The solvent was carefully removed under reduced pressure, and the residue was taken up in dichloromethane and washed with three portions of saturated aqueous K2CO3. The aqueous washings were back extracted with two portions of dichloromethane. The combined organic extracts were dried (MgSO4), filtered, and concentrated under reduced pressure to provide a colorless oil that crystallized on standing under high vacuum. Purification of the crude product was achieved by chromatography on SiO2 (2.5-5% MeOH—CH2Cl2, elution was observed at 285 nm) UV active fractions were reanalyzed by TLC. Two products, 18 and 19, were isolated from this procedure. The major product 18 was a colorless solid 74%: [α]26D +48 (c 0.30, CH2Cl2) 1H NMR (CD2Cl2) δ 0.93 (d, J=6.6 Hz, 3H), 0.95 (d, J=6.6 Hz, 3H), 1.04 (ddd, J=14.6, 8.7, 4.3 Hz, 1H), 1.42 (dd, J=20.2, 11.4 Hz, 1H), 1.59 (ddd, J=13.7, 9.6, 3.3 Hz, 1H), 1.64-1.78 (m, 2H), 1.96 (apparent t, J=11.4 Hz, 1H), 2.27 (br s, 1H), 2.40-2.48 (m, 1H), 2.54 (ddd, J=12.3, 3.7, 2.3 Hz, 1H), 2.60-2.67 (m, 1H), 2.95-3.09 (m, 3H), 3.11 (apparent d, J=11.1 Hz, 1H), 3.35 (ddd, J=10.4, 10.4, 4.5 Hz, 1H), 3.80-3.81 (m, 6H), 6.60 (s, 1H), 6.69 (s, 1H); 13C NMR (CD2Cl2) δ 21.61, 24.02, 25.33, 29.30, 39.68, 40.81, 41.58, 51.83, 55.74, 55.91, 60.02, 60.92, 74.32, 108.42, 111.73, 126.68, 129.76, 147.35, 147.61; HRMS-(ESI+) calcd for (C19H29NO3+H) ([M+H]+ 320.2226, found 320.2242. The minor product 19 was a yellow oil 4%: 1H NMR (CD2Cl2) δ 0.94 (d, J=6.6 Hz, 3H), 0.96 (d, J=6.6 Hz, 3H), 1.13-1.20 (m, 1H), 1.24-1.34 (m, 2H), 1.60-1.77 (m, 2H), 1.89-2.00 (m, 1H) 2.36-2.44 (m, 2H), 2.53 (ddd, J=10.5, 10.5, 3.8 Hz, 1H), 2.58-2.70 (m, 2H), 2.91-2.98 (m, 1H), 2.98-3.09 (m, 1H), 3.48 (apparent d, J=11.6 Hz, 1H), 3.80-3.82 (apparent s, 6H), 4.07 (apparent d, J=3.1 Hz, 1H), 6.60 (s, 1H), 6.68 (s, 1H); 13C NMR (CD2Cl2) δ 22.74, 22.81, 24.87, 29.30, 37.83, 38.87, 39.42, 52.44, 55.76, 55.96, 56.32, 56.43, 67.88, 108.45, 111.78, 127.18, 130.38, 147.30, 147.54.

Workup

  1. customThe solvent was carefully removed under reduced pressure
  2. washwashed with three portions of saturated aqueous K2CO3
  3. extractionThe aqueous washings were back extracted with two portions of dichloromethane
  4. dry with materialThe combined organic extracts were dried (MgSO4)
  5. filtrationfiltered
  6. concentrationconcentrated under reduced pressure
  7. customto provide a colorless oil that
  8. customcrystallized
  9. customPurification of the crude product
  10. customTwo products, 18 and 19, were isolated from this procedure

Sources & evidence

ORD record
ord-b4f043e790bb48d3a843f9f4d0e689b8
Source dataset
uspto-grants-2011_03
Patent number
US07897769B2

Linked notes

Loading…