Dimethyl Sulfate → (S)-(+)-2-ethynyl-3,4-dihydro-6-methoxy-2,5,7,8-tetramethyl-2H-1-benzopyran

HRID 1762330Notes

Reaction equation

HRID 1762330 reaction equation
[C:1]([C@:3]1([CH3:17])[CH2:8][CH2:7][C:6]2[C:9]([CH3:16])=[C:10]([OH:15])[C:11]([CH3:14])=[C:12]([CH3:13])[C:5]=2[O:4]1)#[CH:2].S(OC)(O[CH3:22])(=O)=O.[OH-].[Na+].[OH-].[NH4+]>CC(C)=O>[C:1]([C@:3]1([CH3:17])[CH2:8][CH2:7][C:6]2[C:9]([CH3:16])=[C:10]([O:15][CH3:22])[C:11]([CH3:14])=[C:12]([CH3:13])[C:5]=2[O:4]1)#[CH:2]

Participants

6

Reactant 4

HCID 6497Dimethyl SulfateHCID 14798Sodium HydroxideHCID 14923Ammonium HydroxideHCID 9859440(S)-2-ethynyl-3,4-dihydro-2,5,7,8-tetramethyl-2H-1-benzopyran-6-ol

Product 1

HCID 14478580(S)-(+)-2-ethynyl-3,4-dihydro-6-methoxy-2,5,7,8-tetramethyl-2H-1-benzopyranYield 47%

Reagents, catalysts & solvents 1

HCID 180AcetoneSolvent

Procedure

A solution of (S)-(+)-2-ethynyl-3,4-dihydro-2,5,7,8-tetramethyl-2H-1-benzopyran-6-ol (354 mg, 1.54 mmol) in acetone (9 mL) was treated with dimethyl sulfate (0.8 mL), and 50% NaOH (1.2 mL) for 2 h at 25° C. with stirring. Ammonium hydroxide solution (1.0N, 50 mL) was added, and it was extracted with ehter (3×50 mL). The extracts were combined, washed with 1.0N HCl, water, and dried over MgSO4. It was filtered and concentrated in vacuo to give 400 mg of solid, which or crystallization from ether-hexane (1:12) afforded 141 mg (47%) of (S)-(+)-2-ethynyl-3,4-dihydro-6-methoxy-2,5,7,8-tetramethyl-2H-1-benzopyran as white prisms: mp 94°-97° C., [α]D25 +53.86°, (c 0.4233, CHCl3).

Workup

  1. extractionit was extracted with ehter (3×50 mL)
  2. washwashed with 1.0N HCl, water
  3. dry with materialdried over MgSO4
  4. filtrationIt was filtered
  5. concentrationconcentrated in vacuo
  6. customto give
  7. custom400 mg of solid, which or crystallization from ether-hexane (1:12)

Sources & evidence

ORD record
ord-29c84b821109409fbceffb2ff2719758
Source dataset
uspto-grants-1989_05
Patent number
US04831185

Reaction notes

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