Acetic Anhydride → (R)-(-)-2-(4-Acetoxybenzyl)-3,4-dihydro-2H-benzopyran

HRID 1464821Notes

Reaction equation

HRID 1464821 reaction equation
[OH:1][C:2]1[CH:18]=[CH:17][C:5]([CH2:6][C@H:7]2[CH2:12][CH2:11][C:10]3[CH:13]=[CH:14][CH:15]=[CH:16][C:9]=3[O:8]2)=[CH:4][CH:3]=1.C(N(CC)CC)C.[C:26](OC(=O)C)(=[O:28])[CH3:27]>CN(C)C1C=CN=CC=1.C(Cl)Cl>[C:26]([O:1][C:2]1[CH:18]=[CH:17][C:5]([CH2:6][C@H:7]2[CH2:12][CH2:11][C:10]3[CH:13]=[CH:14][CH:15]=[CH:16][C:9]=3[O:8]2)=[CH:4][CH:3]=1)(=[O:28])[CH3:27]

Participants

6

Reactant 3

HCID 7918Acetic AnhydrideHCID 8471TriethylamineHCID 18653185(R)-(-)-3,4-Dihydro-2-(4-hydroxybenzyl)-2H-benzopyran

Product 1

HCID 18653182(R)-(-)-2-(4-Acetoxybenzyl)-3,4-dihydro-2H-benzopyranYield 70.8%

Reagents, catalysts & solvents 2

HCID 142844-(Dimethylamino)pyridineCatalystHCID 6344DichloromethaneSolvent

Procedure

(R)-(-)-3,4-Dihydro-2-(4-hydroxybenzyl)-2H-benzopyran (5.0 g, 20 mmol), 4-dimethylaminopyridine (240 mg, 2 mmol), triethylamine (2.6 g, 25 mmol) and acetic anhydride (2.9 g, 28 mmol) were dissolved in methylene chloride (75 ml) and stirred at room temperature for 2 hours under a nitrogen atmosphere. The solvent was removed in vacuo and the residue purified on silica gel using hexanes/ethyl acetate (3:1) as eluent to afford an oil which was crystallized from hexanes to yield 4.0 g of the title product, m.p. 64°-65° C.; [α]D -98.9° (c 1.3, MeOH);

Workup

  1. customThe solvent was removed in vacuo
  2. customthe residue purified on silica gel
  3. customto afford an oil which
  4. customwas crystallized from hexanes

Sources & evidence

ORD record
ord-b2a1efbc79dd4d419eb17543de82c6d1
Source dataset
uspto-grants-1994_04
Patent number
US05306726

Reaction notes

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