Oxazole → Methyl 4-butyl-8-(1,3-oxazol-2-yl)-3,4-dihydro-2H-1,4-benzoxazine-6-carboxylate

HRID 348979

Reaction equation

[O:1]1[CH:5]=[CH:4][N:3]=[CH:2]1.C([Li])CCC.[CH2:11]([N:15]1[C:20]2[CH:21]=[C:22]([C:26]([O:28][CH2:29]C)=[O:27])[CH:23]=[C:24](I)[C:19]=2[O:18][CH2:17][CH2:16]1)[CH2:12][CH2:13][CH3:14]>O1CCCC1.C(OCC)(=O)C.[Cl-].[Zn+2].[Cl-]>[CH2:11]([N:15]1[C:20]2[CH:21]=[C:22]([C:26]([O:28][CH3:29])=[O:27])[CH:23]=[C:24]([C:2]3[O:1][CH:5]=[CH:4][N:3]=3)[C:19]=2[O:18][CH2:17][CH2:16]1)[CH2:12][CH2:13][CH3:14]

Participants

Conditions

Temperature: -70 °C

Procedure

To a −70° C. solution of oxazole (227 mg) in tetrahydrofuran (10 mL) was added n-butyllithium (2.5 M in hexanes, 2 mL). After stirred at −70° C. for 30 min, zinc chloride (1 M in ethyl ether, 13 mL) was added. The mixture was warmed to 0° C. for 1 h. To this mixture was then added ethyl 4-butyl-8-iodo-3,4-dihydro-2H-1,4-benzoxazine-6-carboxylate (600 mg, 1.6 mmol) in THF (5 mL) followed by tetrakis triphenylphosphine palladium (0) (115 mg). The mixture was heated at reflux for 3 h, diluted with ethyl acetate (300 mL) and washed with water followed by brine. The organic solution was dried (sodium sulfate) and concentrated under reduced pressure. Purification by silica gel plug (1:1 acetate/hexanes) provided 363 mg of the title compound: 1H NMR (300 MHz, CDCl3) δ 7.96, 7.73, 7.40, 7.28, 4.44, 3.90, 3.43, 3.34, 1.61, 1.41, 0.98.

Workup

temperatureThe mixture was warmed to 0° C. for 1 h
temperatureThe mixture was heated
temperatureat reflux for 3 h
washwashed with water
dry with materialThe organic solution was dried (sodium sulfate)
concentrationconcentrated under reduced pressure
customPurification by silica gel plug (1:1 acetate/hexanes)

Sources & evidence

ORD record: ord-e3cba9d18d30480a81c2788dd1582291
Source dataset: uspto-grants-2007_02
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07176242B2

Linked notes

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