Chlorotrimethylsilane → (+)-Pinanediol 3-(4,4-dimethyl-4,5-dihydro-oxazol-2-yl)phenylboronate

HRID 2077111Notes

Reaction equation

HRID 2077111 reaction equation
[Li]CCCC.Br[C:7]1[CH:8]=[C:9]([C:13]2[O:14][CH2:15][C:16]([CH3:19])([CH3:18])[N:17]=2)[CH:10]=[CH:11][CH:12]=1.C[O:21][B:22](OC)[O:23]C.C[Si](Cl)(C)C.[C:32]12([OH:43])[CH2:40][CH:36]([C:37]1([CH3:39])[CH3:38])[CH2:35][CH2:34][C:33]2([OH:42])[CH3:41]>CCCCCC.C1COCC1.CCOCC>[C:32]12([OH:43])[CH2:40][CH:36]([C:37]1([CH3:39])[CH3:38])[CH2:35][CH2:34][C:33]2([OH:42])[CH3:41].[CH3:18][C:16]1([CH3:19])[CH2:15][O:14][C:13]([C:9]2[CH:8]=[C:7]([B:22]([O-:23])[O-:21])[CH:12]=[CH:11][CH:10]=2)=[N:17]1

Participants

9

Reactant 5

HCID 6397ChlorotrimethylsilaneHCID 8470Trimethyl borateHCID 128530432-(3-Bromophenyl)-4,5-dihydro-4,4-dimethyloxazoleHCID 219250472,6,6-Trimethylbicyclo[3.1.1]heptane-1,2-diolHCID 178418339Butyllithium

Product 1

HCID 131726603(+)-Pinanediol 3-(4,4-dimethyl-4,5-dihydro-oxazol-2-yl)phenylboronateYield 54%

Reagents, catalysts & solvents 3

HCID 3283Diethyl EtherSolventHCID 8028TetrahydrofuranSolvent2×HCID 8058HexaneSolvent

Procedure

n-BuLi (2.5 mL of a 2.5 M solution in hexane, 6.23 mmol) was added dropwise with stirring to a solution of 6 (1.51 g, 5.93 mmol) in THF (9.5 mL) at −78° C. under argon. After 30 min a solution of trimethylborate (0.7 mL, 5.93 mmol) in THF (2 mL) was added and the mixture stirred for 1.5 h; thereafter, the resulting yellow solution was quenched with TMSCl (0.75 mL, 5.93 mmol) and allowed to reach rt. After 1 h (+)-pinanediol (1.01 g, 5.93 mmol) dissolved in a minimum amount of anhydrous Et2O was added one portion to the solution, and then stirred overnight. The reaction mixture was partitioned in Et2O (16 mL) and H2O (10 mL) and the aqueous phase extracted with Et2O (2×10 mL). The combined organic phases were dried on MgSO4, filtered and concentrated to give an orange oil, which was purified by chromatography (7:3 EtPet/EtOAc) and crystallization (EtPet), affording 7 (1.14 g, 54%) as a white crystalline solid, mp 98-101° C., [α]D=+11.2 (c 1.5, CHCl3). IR (KBr): 1646 cm˜1. 1H NMR (CDCl3): δ 0.81 (3H, s, pinanyl CH3), 1.22 (1H, d, J=10.5 Hz, pinanyl Hendo), 1.33 (3H, s, pinanyl CH3), 1.40 (6H, s, 2CH3), 1.50 (3H, s, pinanyl CH3), 1.5-2.5 (5H, m, pinanyl protons), 4.22 (2H, s, CH2O), 4.47 (1H, dd, J=8.8, 2.0 Hz, pinanyl CHOB), 7.43 (1H, t, J=7.7 Hz, H5 arom.), 7.92 (1H, dt, J=7.7, 1.5 Hz, H6 arom.), 8.05 (1H, dt, J=7.7, 1.5 Hz, H4 arom.), 8.43 (1H, br s, H2 arom.). 13C NMR (CDCl3): δ24.4, 26.9, 27.5, 28.8 (2C), 29.1, 35.9, 38.6, 40.0, 51.9, 68.0, 78.8, 79.5, 86.8, 128.1, 131.2, 135.0, 137.8, 162.5, (CB and aromatic quaternary C not seen). EI-MS: m/z 353 (M+), 338 (base peak), 323, 282, 242, 202, 186, 130, 103, 67, 55. Anal. Calcd for C21H28NO3B: C, 71.39; H, 7.99; N 3.96. Found: C, 71.01; H, 8.65; N, 3.89.

Workup

  1. customto reach rt
  2. additionwas added one portion to the solution
  3. stirringstirred overnight
  4. customThe reaction mixture was partitioned in Et2O (16 mL)
  5. extractionH2O (10 mL) and the aqueous phase extracted with Et2O (2×10 mL)
  6. customThe combined organic phases were dried on MgSO4
  7. filtrationfiltered
  8. concentrationconcentrated
  9. customto give an orange oil, which
  10. customwas purified by chromatography (7:3 EtPet/EtOAc) and crystallization (EtPet)

Sources & evidence

ORD record
ord-a0d9be2138254b09bcdf42e11d864971
Source dataset
uspto-grants-2011_04
Patent number
US07928129B1

Reaction notes

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