Benzene, 1,2-dibromo-4,5-dimethyl- → HCID 178419162, compound

HRID 713831Notes

Reaction equation

HRID 713831 reaction equation
[BH3:1].[C:2]1([PH:8][C:9]2[CH:14]=[CH:13][CH:12]=[CH:11][CH:10]=2)[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.[Li]CCCC.Br[C:21]1[CH:22]=[C:23]([CH3:29])[C:24]([CH3:28])=[CH:25][C:26]=1[Br:27]>C1COCC1>[BH3:1].[Br:27][C:26]1[CH:25]=[C:24]([CH3:28])[C:23]([CH3:29])=[CH:22][C:21]=1[P:8]([C:9]1[CH:10]=[CH:11][CH:12]=[CH:13][CH:14]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1

Participants

5

Reactant 3

HCID 34347Benzene, 1,2-dibromo-4,5-dimethyl-HCID 13485179HCID 13485179, compoundHCID 178418339Butyllithium2×

Product 1

HCID 178419162HCID 178419162, compoundYield 56%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

To a solution of diphenylphosphine borane (V-a) (0.17 g, 0.83 mmol) in dry THF (2 mL) was added dropwise under argon at −78° C. n-BuLi (0.83 mmol). The resulting solution was stirred at this temperature during one hour and 4,5-dibromo-o-xylene (VI-b) (0.31 g, 1.16 mmol) was then added dropwise followed by n-BuLi (0.17 mmol). After one hour at −78° C., the reaction mixture was quenched with water (10 mL) and extracted with methylene chloride (3×10 mL). The organic phases were dried over MgSO4, filtered and the solvent evaporated giving a residue which was purified by column chromatography on silica gel using petroleum ether/methylene chloride 3:1 as eluent. Analytical pure sample can be obtained by recrystallization in methylene chloride/hexane. White solid; yield 56%; Rf 0.45 (petroleum ether/ethyl acetate 3:1); IR (neat) 3050, 2986, 2946, 2917, 2417, 2388, 2357, 1588, 1481, 1471, 1436, 1343, 1136, 1125, 1102, 1062, 1028, 999, 923, 877, 749, 734, 701, 692 cm−1; 1H NMR (300MHz, CDCl3) δ 2.17 (s, 3H, CH3), 2.29 (s, 3H, CH3), 7.21 (d, J=12.3 Hz, Harom), 7.43-7.56 (m, 7H, Harom), 7.65-7.72 (m, 4H, Harom); 13C NMR (75.5 MHz, CDCl3) δ 19.4 (CH3), 19.5 (CH3), 124.7 (d, J=4.4 Hz, Carom), 131.1 (d, J=2.5 Hz, Carom), 133.2 (d, J=9.6 Hz, Carom), 135.9 (d, J=6.1 Hz, Carom), 136.3 (d, J=9.9 Hz, Carom), 137.8 (d, J=11.8 Hz, Carom), 142.6 (d, J=2.2 Hz, Carom); 31P NMR (121 MHz, CDCl3) δ 25.5; HRMS calcd for C20H21PBBrNa (M+Na)+ 405.0553, found 405.0563; Anal calcd for C20H21PBBr: C, 62.71; H, 5.53; found: C, 62.86; H, 5.58.

Workup

  1. waitAfter one hour at −78° C.
  2. customthe reaction mixture was quenched with water (10 mL)
  3. extractionextracted with methylene chloride (3×10 mL)
  4. dry with materialThe organic phases were dried over MgSO4
  5. filtrationfiltered
  6. customthe solvent evaporated
  7. customgiving a residue which
  8. customwas purified by column chromatography on silica gel
  9. customAnalytical pure sample can be obtained by recrystallization in methylene chloride/hexane

Sources & evidence

ORD record
ord-3466b8c768464a5084ca4a33ef967ca4
Source dataset
uspto-grants-2015_11
Patent number
US09186661B2

Reaction notes

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