Potassium Carbonate → [(2,3-Dihydro-3-oxo-1H-naphtho[2,1-b]pyran-8-yl)oxy]acetic Acid 1,1-Dimethylethyl Ester

HRID 1648104Notes

Reaction equation

[OH:1][C:2]1[CH:3]=[C:4]2[C:13](=[CH:14][CH:15]=1)[C:12]1[CH2:11][CH2:10][C:9](=[O:16])[O:8][C:7]=1[CH:6]=[CH:5]2.Br[CH2:18][C:19]([O:21][C:22]([CH3:25])([CH3:24])[CH3:23])=[O:20].C(=O)([O-])[O-].[K+].[K+]>CC(=O)CC>[CH3:23][C:22]([O:21][C:19](=[O:20])[CH2:18][O:1][C:2]1[CH:3]=[C:4]2[C:13](=[CH:14][CH:15]=1)[C:12]1[CH2:11][CH2:10][C:9](=[O:16])[O:8][C:7]=1[CH:6]=[CH:5]2)([CH3:25])[CH3:24]

Participants

Conditions

Temperature: 60 °C

Procedure

A mixture of 2.18 g (10.2 mmol) of 1,2-dihydro-8-hydroxy-3H-naphtho[2,1-b]pyran-3-one from the preceding example, 4.84 g (24.8 mmol) of t-butyl bromoacetate, 5.63 g (40.7 mmol) of anhydrous granular potassium carbonate and 55.5 mL of 2-butanone was heated at 60° C. for 24 hr. A second portion of t-butyl bromoacetate (0.5 mL, 3.1 mmol) was added and the reaction was allowed to proceed for another 17 hr. After being cooled to room temperature, the mixture was filtered and the solids were washed with ethyl acetate and ether. The filtrate and washes were combined and concentrated in vacuo, and the crude product was flash chromatographed on 360 g of silica gel, eluting with hexane-ethyl acetate (7:1 then 6:1) affording 3.04 g (91.0%) of the title compound as a white solid, mp 95°-96° C.

Workup

temperatureAfter being cooled to room temperature
filtrationthe mixture was filtered
washthe solids were washed with ethyl acetate and ether
concentrationconcentrated in vacuo
customchromatographed on 360 g of silica gel
washeluting with hexane-ethyl acetate (7:1

Sources & evidence

ORD record: ord-d966d50141bb4db688e42da38fa61368
Source dataset: uspto-grants-1995_07
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US05434186

Reaction notes

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