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

HRID 2072618Notes

Reaction equation

HRID 2072618 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 ether (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 ether (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-4fa00288a5324d4090daf476a6a65d78
Source dataset
uspto-grants-1990_04
Patent number
US04913851

Reaction notes

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