Boron tribromide → (4aR,6aR,11aR,11bR)-7,9-Dihydroxy-4,4,6a,11b-tetramethyl-1,2,4,4a,5,6,6a,11,11a,11b-decahydro-benzo[a]fluoren-3-one

HRID 1466729Notes

Reaction equation

HRID 1466729 reaction equation
C[O:2][C:3]1[CH:15]=[C:14]([O:16]C)[CH:13]=[C:12]2[C:4]=1[C@@:5]1([CH3:26])[C@H:10]([CH2:11]2)[C@@:9]2([CH3:25])[CH2:18][CH2:19][C:20](=[O:24])[C:21]([CH3:23])([CH3:22])[C@@H:8]2[CH2:7][CH2:6]1.B(Br)(Br)Br>C(Cl)Cl>[OH:2][C:3]1[CH:15]=[C:14]([OH:16])[CH:13]=[C:12]2[C:4]=1[C@@:5]1([CH3:26])[C@H:10]([CH2:11]2)[C@@:9]2([CH3:25])[CH2:18][CH2:19][C:20](=[O:24])[C:21]([CH3:22])([CH3:23])[C@@H:8]2[CH2:7][CH2:6]1

Participants

4

Reactant 2

HCID 25134Boron tribromideHCID 56837781(4aR,6aR,11aR,11bR)-7,9-Dimethoxy-4,4,6a,11b-tetramethyl-1,2,4,4a,5,6,6a,11,11a,11b-decahydro-benzo[a]fluoren-3-one2×

Product 1

HCID 56837782(4aR,6aR,11aR,11bR)-7,9-Dihydroxy-4,4,6a,11b-tetramethyl-1,2,4,4a,5,6,6a,11,11a,11b-decahydro-benzo[a]fluoren-3-oneYield 86.3%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Conditions

Temperature
0 °C

Procedure

To ketone 6b (240 mg, 0.67 mmol) dissolved in 20 mL of methylene chloride stirring at 0° C. was added 2.7 mL of BBr3 (1.0 M in methylene chloride, 2.69 mmol). After stirring for one hour at 0° C., 6b was still present, and the reaction was allowed to reach room temperature over the next two hours. The reaction was then quenched with methanol, and water was added to the mixture. The aqueous phase was then extracted 3 times with methylene chloride (3×50 mL). The combined organic extracts were dried with MgSO4 and concentrated. The crude mixture was purified by flash chromatography to give 7b (190 mg, 0.578 mmol, 86%) as a white crystalline solid. 1H NMR (400 MHz, (CD3)2CO) δ 7.76 (s, 1H), 7.73 (s, 1H), 6.24 (t, J=0.96 Hz, 1H), 6.13 (d, J=1.6 Hz, 1H)), 2.66-2.61 (m, 1H), 2.59-2.52 (m, 2H), 2.49-2.46 (m, 1H), 2.44-2.37 (m, 1H), 1.86-1.82 (m, 1H), 1.81-1.77 (m, 1H), 1.76-1.71 (m, 1H), 1.67-1.55 (m, 4H), 1.15 (s, 3H), 1.13 (s, 3H), 1.07 (s, 3H), 1.09 (s, 3H); 13C NMR (100 MHz, (CD3)2CO) δ 216.9, 158.5, 154.8, 146.7, 131.9, 105.8, 102.8, 65.4, 57.2, 48.9, 47.3, 40.5, 39.6, 38.0, 35.4, 30.9, 27.9, 22.2, 22.1, 21.3, 16.9. ESIMS [M+Na]+ calcd for C21H28O3Na 351.1936, found 351.1929. [α]24D=+24.07°.

Workup

  1. customto reach room temperature over the next two hours
  2. customThe reaction was then quenched with methanol, and water
  3. additionwas added to the mixture
  4. extractionThe aqueous phase was then extracted 3 times with methylene chloride (3×50 mL)
  5. dry with materialThe combined organic extracts were dried with MgSO4
  6. concentrationconcentrated
  7. customThe crude mixture was purified by flash chromatography

Sources & evidence

ORD record
ord-62963b6f9a9943e7b8cb73f1e16c0fef
Source dataset
uspto-grants-2015_04
Patent number
US09000050B2

Reaction notes

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