Potassium Carbonate → tert-butyl 6-benzyloxy-2H-1-benzopyran-3-carboxylate

HRID 466171Notes

Reaction equation

[CH2:1]([O:8][C:9]1[CH:10]=[CH:11][C:12]([OH:17])=[C:13]([CH:16]=1)[CH:14]=O)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.C(=O)([O-])[O-].[K+].[K+].[C:24]([O:28][C:29]([CH3:32])([CH3:31])[CH3:30])(=[O:27])[CH:25]=[CH2:26]>CN(C=O)C>[CH2:1]([O:8][C:9]1[CH:10]=[CH:11][C:12]2[O:17][CH2:26][C:25]([C:24]([O:28][C:29]([CH3:32])([CH3:31])[CH3:30])=[O:27])=[CH:14][C:13]=2[CH:16]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1

Participants

Conditions

Temperature: 100 °C

Procedure

5-Benzyloxy-2-hydroxybenzaldehyde (2.01 g, 8.80 mmol) is dissolved in 30 ml of DMF and treated successively with potassium carbonate (1.22 g, 8.80 mmol) and tert-butyl acrylate (1.22 g, 13.2 mmol). The mixture is heated at 100° C. for 1 hour. The temperature is gradually raised to 135° C. over a period of 2 hours, and held at 135° C. for 1 hour. The resultant dark mixture is cooled and evaporated to remove most of DMF. The residue is partitioned between ether and water, and the aqueous phase is discarded. The organic layer is dried (MgSO4), evaporated and purified by silica gel chromatography (6% ethyl acetate/hexane) to give tert-butyl 6-benzyloxy-2H-1-benzopyran-3-carboxylate as a yellow crystalline solid, m.p. 64°-67° C.

Workup

temperatureThe temperature is gradually raised to 135° C. over a period of 2 hours
temperatureThe resultant dark mixture is cooled
customevaporated
customto remove most of DMF
customThe residue is partitioned between ether and water
dry with materialThe organic layer is dried (MgSO4)
customevaporated
custompurified by silica gel chromatography (6% ethyl acetate/hexane)

Sources & evidence

ORD record: ord-a50e873b061b4749954183133f982adf
Source dataset: uspto-grants-1992_10
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US05155130

Reaction notes

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