Acetyl chloride → 1-(3,4-dihydro-2H-1-benzopyran-6-yl)ethan-1-one

HRID 1669168Notes

Reaction equation

HRID 1669168 reaction equation
[Al+3].[Cl-].[Cl-].[Cl-].[C:5](Cl)([CH3:7])=[O:6].[O:9]1[C:18]2[C:13](=[CH:14][CH:15]=[CH:16][CH:17]=2)[CH2:12][CH2:11][CH2:10]1>C(Cl)Cl>[O:9]1[C:18]2[C:13](=[CH:14][C:15]([C:5](=[O:6])[CH3:7])=[CH:16][CH:17]=2)[CH2:12][CH2:11][CH2:10]1

Participants

5

Reactant 3

HCID 6367Acetyl chlorideHCID 136319ChromanHCID 6451240Aluminum(III) Chloride

Product 1

HCID 123570181-(3,4-dihydro-2H-1-benzopyran-6-yl)ethan-1-oneYield 80.1%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent2×

Procedure

AlCl3 (11.8 g, 88.2 mmol) was added in small portions to a stirred solution of AcCl (11.9 mL, 167.5 mmol) in dry DCM (250 mL) at −10° C. and the mixture stirred until homogeneous (15 min). The solution was added, via a cannula, to a stirred solution of chroman (229) (11.8 g, 88.2 mmol) in dry DCM (200 mL) at −10° C. and the solution stirred for 30 min at −10° C. and then poured into ice/cHCl (5:1 v/v, 1.5 L). The mixture was stirred for 2 h, extracted with DCM (3×100 mL), the combined organic fraction dried and the solvent evaporated. The residue was purified by chromatography, eluting with a gradient (10-20%) of EtOAc/pet. ether, to give 1-(3,4-dihydro-2H-chromen-6-yl)ethanone (230) (12.45 g, 80%) as a white solid: 1H NMR δ 7.68-7.22 (m, 2H, H-5, H-7), 6.82 (d, J=9.2 Hz, 1H, H-8), 4.24 (br dd, J=5.3, 5.2 Hz, 2H, H 2), 2.83 (br t, J=6.5 Hz, 2H, H-4), 2.53 (s, 3H, CH3), 2.00-2.06 (m, 2H, H-3).

Workup

  1. stirringthe solution stirred for 30 min at −10° C.
  2. stirringThe mixture was stirred for 2 h
  3. extractionextracted with DCM (3×100 mL)
  4. customthe combined organic fraction dried
  5. customthe solvent evaporated
  6. customThe residue was purified by chromatography
  7. washeluting with a gradient (10-20%) of EtOAc/pet. ether

Sources & evidence

ORD record
ord-9ddbf305610c4993be7d9c0d9bdff9fe
Source dataset
uspto-grants-2011_08
Patent number
US07989451B2

Reaction notes

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